Category Mobile App Development

Python vs Node.js – Which One to Choose in 2023?

How to Choose Between Python and Node.js

Python and Node.js are both popular programming languages that can be used to create web applications, with each being more suitable for certain types of projects. Many users choose to use one or the other, but what should they choose in 2023? It depends. With both languages being powerful and with technologies quickly changing, the choice ultimately comes down to your skill level, the project’s complexity, and budget.

What is Python?

Python is a popular general-purpose computer language with a wide variety of uses. It offers high-level data structures, dynamic type, dynamic binding, and many other features that make it ideal for complex program development and “glue code” that connects components. It can also run C or C++ applications and make system calls to practically any operating system. Python is a popular programming language due to its versatility and ability to operate on almost any system architecture.

What is Node.js?

Node.js is a JavaScript-based framework that may be used to create online chat applications, video streaming websites, single-page applications, and various other I/O-intensive web applications and web apps. It’s built on Google Chrome’s JavaScript V8 Engine and is utilized by both vast corporations and young businesses (Netflix, Paypal, NASA, and Walmart, to name a few).

Thousands of developers use Node.js because it is open-source and entirely free. It has several benefits over other server-side technologies like Java or PHP, making it a preferable option.

Comparing Python and Node.js

If you’re a developer, you’ll know that there are many options when it comes to choosing a language to write your code in. Node.js and Python are two of the most popular choices for developers—and a good reason.

Both Python and Node.js are powerful web development environments with a lot of potential for large and small-scale projects. Python and Node.js have their differences, of course, and choosing the right one for your project is all about knowing what makes each unique—and what you’ll need to create the project you have in mind.


There are a few similarities between Python and Node.js regarding development architecture. Both utilize event-driven, non-blocking I/O (input/output) calls. This means that the programming language can handle multiple requests at once without the need to wait for previous requests to finish up.

This parallelism allows developers to complete tasks more efficiently while freeing up server resources that other processes would have used in earlier web development languages.

Python is also less resource-intensive than Node.js. The setup takes quicker and simpler since less space and resources are utilized. Node.js, on the other hand, requires more resources and takes longer to set up than Python.


Libraries are responsible for the rapid advancement of app development technologies in recent decades. The Node Package Manager manages a large number of well-documented libraries in Node.js. NPM is the world’s biggest package repository, with over 350,000 packages.

Pip, which stands for ‘Pip Installs Packages,’ manages Python’s libraries. Python libraries are well-documented and simple to deploy, according to industry standards. This is often true, but not in the case of new libraries. New technologies are often less thoroughly documented than older technologies, making newer libraries less dependable.

With both technologies, you’ll have many alternatives for libraries and ancillary-development tools. Both are equally effective!

Error Handling

Nothing beats the feeling of writing error-free code. As a result, CTOs will always choose the language with the best error-handling methods. Finding faults and problems in the code might be time-consuming using Node.js’ parallel-processing functionality.

Python’s simpler syntax, low-code interface, and absence of concurrent processes help when looking for problems and mistakes in the code. As such, it makes it popular within the small business demographic..

If error handling is a critical factor in your selection, you may have already deduced that Python has a considerable advantage over Node.js.

Data Processing

This may seem to be a minor factor, but it is important. A language/environment with higher data processing capability is naturally more efficient and adaptable.

If your app’s use case requires a lot of data, Node.js should be your first pick. The runtime environment’s technology makes it excellent for programs where data is often transferred and managed. Python is sluggish in processing data because it has a basic syntax and just one thread running at a time.

Node.js is the more efficient competitor because of its parallel processing and smooth I/O operations.


As you can see, both languages are impressive and have numerous advantages. Developing an app in either of them is a wise choice, depending on the needs of your business. Both are easy to learn for experienced developers—but much more difficult for newbies.

Node.js is more versatile and has more development resources than Python did in 2011. It has one distinct advantage: it runs on JavaScript, the most popular programming language worldwide and most developers’ primary language. This makes Node.js accessible to a larger number of developers: not just Java and C++ users but also Python and JavaScript users.

This makes Node.js a valuable development tool for companies that need to reach a wide audience. Browse application of Python and Node.js development to find more information.

What Questions to Ask a Software Development Company

One of the best strategies of getting your digital product off the ground quickly and efficiently  is to outsource the development to an experienced software development company. Building a digital product like a mobile app or web-based application requires significant planning and investment, and while searching for the right company, you will notice there are thousands of companies to choose from. How can you truly decide which development partner is right for you?

8 Questions to ask before outsourcing your digital product development

Answers are only as good as the questions you ask, and if you ask poor questions, you are going to get poor answers. In this article, we have added 8 questions you should ask your potential developer. These will help you decide if the company you are talking to is right for your project.

1. Have you developed applications with similar solution types to my product?

The focus here is on the solution type. It is far more beneficial for you if the company has built products that offer the same solution you are looking for rather than just working in the same industry. Try and find out how the solutions in the application solved the business problems, and find similarities in your product.

2. Do you have in-house developers or do you outsource the work to other companies and freelancers?

There are some companies in the industry that will represent themselves as companies registered in the US, UK or Western Europe and their hourly rates are reflective of those countries, but they outsource the web development to third-party companies or freelancers from other countries. This can cause a major risk to your project because the company you deal with doesn’t have complete control over the workforce used, and there can be inconsistencies in the procedure.

3. How will you ensure to stay within my budget?

Beware if the answer is ‘a fixed price.’ It might seem like the safest choice for you but let’s consider why it could be the worst decision for your project. Most custom software development requires multiple developers to build multiple features over multiple months. No app is ever the same so it is impossible to know exactly how long it will take or how much it will cost.

If the web development company offers a fixed price, they either have enough profit margin to offset any delays, or “scope creep” meaning you are overpaying for their service. Or, they will run out of budget at some point in the development process and compromise the quality of the development process, or fail to deliver at all. The worst case scenario is that you end up in a bitter legal dispute half way through the project which forces you to pay extra for things which are ‘outside the scope’ creating a very bad business relationship.

Look for a developer which has a clear rate card and understands the team lineup required and can estimate the length of time required based on similar solution types (refer question 1).

4. Will I own the Intellectual Property rights and when will I get the source code?

If you have had a billion dollar idea and decided to invest in building a digital product, the worst possible outcome is to get to a point where you realize ‘in the fineprint’ that you don’t actually own the source code.

Ensure that the software development company has a clear process of transferring the Intellectual Property rights to you and that they have no legal rights of owning your source code. The process of regularly transferring the actual source code and ownership of it should be very clear.

Some companies will offer you favorable conditions in return for part ownership of the source code but you need to weigh up whether you want to give control of your source code to someone you do not really know. In some cases, this might be a good solution for your project but you should seek legal advice before going down this route.

5. What is your quality assurance process?

Some development companies may only have developers and don’t place a large emphasis on QA testing during the process. Many companies will offer testing services after the development has finished, but you should look for a company that treats testing as an integral part of the development process.

QA stands for Quality Assurance and if quality is to be assured, it is vital for QA engineers to understand the goals of the project from the very beginning so they can help create the right test scenarios and constantly perform tests throughout development.

6. What tech stack will be used for my project?

This is kind of a “trick question” to see how the company treats technical recommendations. Of course, based on your high-level requirements, a reputable software development company will already have an idea of what technology could be used to create your digital product. But, beware of a company that will push a certain tech on you from the very beginning without understanding the business goals of your project, or knowing the ‘pain points’ of the target users.

One technology solution may be better suited to one project but not suitable for the next. Technology should always be secondary to the business model. For instance, if a company only has React Native mobile developers, then they will try to push React Native as the ‘best’ solution for your project, when in reality when video conferencing features or Bluetooth integrations are required a native approach may be better. It is important for you, at this stage, to see if they are open to different technologies, how they will identify the most suitable tech and whether they have developers in multiple different technologies.

7. Will I have access to the team throughout the development process?

A common frustration for many people who decide to outsource their development is access to the team. Very often in custom software development, you need to ask questions, make changes, get updates and seek advice. This is almost impossible if you can’t speak to the team.

Not being able to speak to the team can be a result of a lack of language skills, teams scattered across multiple time zones or a lack of communication channels set up at the beginning of the development. If there is no regular contact with the team it can be difficult when things go wrong, and at a time when you need answers ‘radio silence’ is your worst enemy. Ensure there is a clear process for regular meetings, reports and access to the team.

8. Why should I work with you guys?

After getting answers to all the questions listed above, the final question to ask is “Why should I work with you guys?” If you are interviewing many reputable companies, the final decision of which company to work with can be really difficult. It may just come down to the rapport you have been able to build during the RFP process.

When they answer this question, listen out for things which differentiate their company to others you have spoken to. What you should be looking for is a partner that wants to work with you long-term and will become a crucial part of your business, can add value to your team and will help your business scale, so that in the future you can hire your own internal team to grow the product for years to come.

Exploring Forms in Angular – Types, Benefits and Differences

While developing a web application, or setting dynamic pages and meta tags we need to deal with multiple input elements and value types, such limitations could seriously hinder our work – in terms of either data flow control, data validation, or user experience.

This article is an excerpt from the book, ASP.NET Core 5 and Angular, Fourth Edition by Valerio De Sanctis – A revised edition of a bestseller that includes coverage of the Angular routing module, expanded discussion on the Angular CLI, and detailed instructions for deploying apps on Azure, as well as both Windows and Linux.

Sure, we could easily work around most of the issues by implementing some custom methods within our form-based components we could throw some errors such as isValid(), isNumber(), and so on here and there, and then hook them up to our template syntax and show/hide the validation messages with the help of structural directives such as *ngIf, *ngFor, and the like. However, it would be a horrible way to address our problem; we didn’t choose a feature-rich client-side framework such as Angular to work that way.

Luckily enough, we have no reason to do that since Angular provides us with a couple of alternative strategies to deal with these common form-related scenarios:

  • Template-Driven Forms
  • Model-Driven Forms, also known as Reactive Forms

Both are highly coupled with the framework and thus extremely viable; they both belong to the @angular/forms library and share a common set of form control classes. However, they also have their own specific sets of features, along with their pros and cons, which could ultimately lead to us choosing one of them.

Let’s try to quickly summarize these differences.

Template-Driven Forms

If you’ve come from AngularJS, there’s a high chance that the Template-Driven approach will ring a bell or two. As the name implies, Template-Driven Forms host most of the logic in the template code; working with a Template-Driven Form means:

  • Building the form in the .html template file
  • Binding data to the various input fields using ngModel instance
  • Using a dedicated ngForm object related to the whole form and containing all the inputs, with each being accessible through their name.

These things need to be done to perform the required validity checks. To understand this, here’s what a Template-Driven Form looks like:

<form novalidate autocomplete="off" #form="ngForm"

<input type="text" name="name" value="" required  
placeholder="Insert the city name..."   
[(ngModel)]="city.Name" #title="ngModel"  

<span *ngIf="(name.touched || name.dirty) &&   
        Name is a required field: please enter a valid city name.  

<button type="submit" name="btnSubmit"   

Here, we can access any element, including the form itself, with some convenient aliases – the attributes with the # sign – and check for their current states to create our own validation workflow.

These states are provided by the framework and will change in real-time, depending on various things: touched, for example, becomes True when the control has been visited at least once; dirty, which is the opposite of pristine, means that the control value has changed, and so on. We used both touched and dirty in the preceding example because we want our validation message to only be shown if the user moves their focus to the <input name=”name”> and then goes away, leaving it blank by either deleting its value or not setting it.

These are Template-Driven Forms in a nutshell; now that we’ve had an overall look at them, let’s try to summarize the pros and cons of this approach. Here are the main advantages of Template-Driven Forms:

  • Template-Driven Forms are very easy to write. We can recycle most of our HTML knowledge (assuming that we have any). On top of that, if we come from AngularJS, we already know how well we can make them work once we’ve mastered the technique.
  • They are rather easy to read and understand, at least from an HTML point of view; we have a plain, understandable HTML structure containing all the input fields and validators, one after another. Each element will have a name, a two-way binding with the underlying ngModel, and (possibly) Template-Driven logic built upon aliases that have been hooked to other elements that we can also see, or to the form itself.

Here are their weaknesses:

  • Template-Driven Forms require a lot of HTML code, which can be rather difficult to maintain and is generally more error-prone than pure TypeScript.
  • For the same reason, these forms cannot be unit tested. We have no way to test their validators or to ensure that the logic we implemented will work, other than running an end-to-end test with our browser, which is hardly ideal for complex forms.
  • Their readability will quickly drop as we add more and more validators and input tags. Keeping all their logic within the template might be fine for small forms, but it does not scale well when dealing with complex data items.

Ultimately, we can say that Template-Driven Forms might be the way to go when we need to build small forms with simple data validation rules, where we can benefit more from their simplicity. On top of that, they are quite like the typical HTML code we’re already used to (assuming that we do have a plain HTML development background); we just need to learn how to decorate the standard <form> and <input> elements with aliases and throw in some validators handled by structural directives such as the ones we’ve already seen, and we’ll be set in (almost) no time.

For additional information on Template-Driven Forms, we highly recommend that you read the official Angular documentation at: 

That being said; the lack of unit testing, the HTML code bloat that they will eventually produce, and the scaling difficulties will eventually lead us toward an alternative approach for any non-trivial form.

Model-Driven/Reactive Forms

The Model-Driven approach was specifically added in Angular 2+ to address the known limitations of Template-Driven Forms. The forms that are implemented with this alternative method are known as Model-Driven Forms or Reactive Forms, which are the exact same thing.

The main difference here is that (almost) nothing happens in the template, which acts as a mere reference to a more complex TypeScript object that gets defined, instantiated, and configured programmatically within the component class: the form model.

To understand the overall concept, let’s try to rewrite the previous form in a Model-Driven/Reactive way (the relevant parts are highlighted). The outcome of doing this is as follows:

<form [formGroup]="form" (ngSubmit)="onSubmit()"> 

<input formControlName="name" required /> 

<span *ngIf="(form.get('name').touched || form.get('name').dirty)           
&& form.get('name').errors?.required">          
Name is a required field: please enter a valid city name.  

<button type="submit" name="btnSubmit"          

As we can see, the amount of required code is much lower.  Here’s the underlying form model that we will define in the component class file (the relevant parts are highlighted in the following code):

import { FormGroup, FormControl } from '@angular/forms'; 

class ModelFormComponent implements OnInit {  
form: FormGroup;   
     ngOnInit() {  
    this.form = new FormGroup({  
       title: new FormControl()  

Let’s try to understand what’s happening here:

  • The form property is an instance of FormGroup and represents the form itself.
  • FormGroup, as the name suggests, is a container of form controls sharing the same purpose. As we can see, the form itself acts as a FormGroup, which means that we can nest FormGroup objects inside other FormGroup objects (we didn’t do that in our sample, though).
  • Each data input element in the form template – in the preceding code, name – is represented by an instance of FormControl.
  • Each FormControl instance encapsulates the related control’s current state, such as valid, invalid, touched, and dirty, including its actual value.
  • Each FormGroup instance encapsulates the state of each child control, meaning that it will only be valid if/when all its children are also valid.

Also, note that we have no way of accessing the FormControls directly like we were doing in Template-Driven Forms; we have to retrieve them using the .get() method of the main FormGroup, which is the form itself.

At first glance, the Model-Driven template doesn’t seem too different from the Template-Driven one; we still have a <form> element, an <input> element hooked to a <span> validator, and a submit button; on top of that, checking the state of the input elements takes a bigger amount of source code since they have no aliases we can use. What’s the real deal, then?

To help us visualize the difference, let’s look at the following diagrams: here’s a schema depicting how Template-Driven Forms work:

By looking at the arrows, we can easily see that, in Template-Driven Forms, everything happens in the template; the HTML form elements are directly bound to the DataModel component represented by a property filled with an asynchronous HTML request to the Web Server, much like we did with our cities and country table.

That DataModel will be updated as soon as the user changes something, that is, unless a validator prevents them from doing that. If we think about it, we can easily understand how there isn’t a single part of the whole workflow that happens to be under our control; Angular handles everything by itself using the information in the data bindings defined within our template.

This is what Template-Driven actually means: the template is calling the shots.  Now, let’s take a look at the Model-Driven Forms (or Reactive Forms) approach:

As we can see, the arrows depicting the Model-Driven Forms workflow tell a whole different story. They show how the data flows between the DataModel component – which we get from the Web Server – and a UI-oriented form model that retains the states and the values of the HTML form (and its children input elements) that are presented to the user. This means that we’ll be able to get in-between the data and the form control objects and perform a number of tasks firsthand: push and pull data, detect and react to user changes, implement our own validation logic, perform unit tests, and so on.

Instead of being superseded by a template that’s not under our control, we can track and influence the workflow programmatically, since the form model that calls the shots is also a TypeScript class; that’s what Model-Driven Forms are about. This also explains why they are also called Reactive Forms – an explicit reference to the Reactive programming style that favors explicit data handling and change management throughout the workflow.


In this article, we focused on the Angular framework and the two form design models it offers: the Template-Driven approach, mostly inherited from AngularJS, and the Model-Driven or Reactive alternative. We took some valuable time to analyze the pros and cons provided by both, and then we made a detailed comparison of the underlying logic and workflow. At the end of the day, we chose the Reactive way, as it gives the developer more control and enforces a more consistent separation of duties between the Data Model and the Form Model.


What Is Rapid Application Development (RAD)?

If you’re looking for a faster method of application development, you’ll want to choose something other than the Waterfall methodology, which requires sticking to a planned schedule and doesn’t allow for continuous iterations. That means you’ll end up restarting the development from the beginning every time the client suggests changes.

Rapid application development (RAD), also called rapid-application building (RAB), is better than Waterfall! Though it’s been around for a while, the RAD approach is still popular among those looking for agile methods of application development to keep pace with growing business and client needs.

In the case of you’re searching out a quicker method of application improvement, you’ll want to select something other than the Waterfall method, which requires sticking to a planned agenda and doesn’t allow for non-stop iterations. That means you’ll grow to be restarting the improvement from the beginning each time the customer indicates adjustments.

What Is Rapid Application Improvement, and What Are Its Blessings?

Rapid Application Development (RAD) is a shape of an agile software improvement method that prioritizes speedy prototype discharges and emphasis. In contrast to the Waterfall method, RAD emphasizes using software programs and user comments over strict making plans and necessities recording.


Key Blessings and Advantages of RAD

  • Enhanced flexibility and adaptability as dedicated software developers could make adjustments speedy at some point in the improvement method.
  • Quick cycles that reduce improvement time and accelerate delivery.
  • Encouragement of code reuse, which means less manual coding, much less room for errors, and shorter testing times. Increased consumer pleasure due to high-stage collaboration and coordination between stakeholders (web or reactjs developers, customers, and stop users).
  • Better threat control as partners can speak and address code vulnerabilities while maintaining improvement strategies going.
  • Fewer shocks as, not like the Waterfall approach, RAD consists of integrations early on within the software development manner.


Steps or Stages in RAD

Stage 1 — Characterize and Finalize Undertaking Necessities

During this progression, experienced web developers sit together to define and finalize undertaking requirements inclusive of challenge desires, expectancies, courses of events, and price go. When you have got defined and perused out each factor of the venture’s necessities, you may are be looking for control approvals.

Stage 2 — Begin Building Prototypes

As quickly as you end scoping the project, you could start web development. Planners and builders will work carefully with clients to make and improve upon working prototypes until the final product is arranged.

Stage 3 — Gather User Feedback

In this progression, models and beta structures are transformed into operating models. Top remote Developers then collect feedback from customers to change and enhance prototypes and make high-quality feasible products.

Stage 4 — Test, Test, Check

This step requires you to test your software program product and make certain that each one its transferring components paintings together as consistent with client expectancies. Proceed to incorporate consumer comments because the code is tested and retested for its smooth functioning.

Step 5 — Present Your System

This is the very last step before the completed product is going to launch. It includes statistics conversion and person training.


Are you RAD-ready?

  • Do you need to develop a software product within a short span of time?
  • Do you have an experienced team of developers, coders, and designers who can carry out the work on your timeline?
  • Are you or your client open to adopting RAD and available for collaboration throughout the software development process?
  • Do you have the right tools and technology to implement RAD?


Further steps

Adopting a new process requires everyone involved in SDLC, including your team and your client. If you’ve decided the RAD approach is right for you, here’s what you should do next:

  • Make sure your team has an all-hands-on-deck mindset. Talk to your team about the benefits of the new approach and listen to and address their concerns.
  • Ensure that all stakeholders are willing to adhere to the project timelines.
  • Explore application development software and tools. Invest in one that fits your business’s budget and requirements to be able to effectively apply this methodology.
  • Ensure that the development team is fast in communication, passionate and committed for the delivery


Source credit: What Is Rapid Application Development (RAD)?

What Things to Avoid When launching Mobile App

Are you finished with your Mobile app development process and looking for thousands of app downloads now? Definitely, you want audience to find your mobile application and download it to use with great features. Nevertheless there are various mistakes that novices make when launching a new mobile app.

Here are some major mistakes that you should avoid to save cost and time when launching an app. For a better experience and getting your app built timely you can find and hire the best mobile app development company.  To help you here are some major mistakes that you should avoid to save cost and time when launching an app.

You wait too long to market

You are expecting thousands of downloads as soon as your iOS or Android mobile app goes live in app store but there are too many similar apps competing for user’s attention already. As per recent report, approx. 2.47 million apps are on Google play and 1.8 million apps are on Apple’s App store. So to be more precise, you’ll be challenging with this calculation.

You can expect more competition even tighter each month with new launching and upcoming apps. If you don’t have unique and killer marketing plan for your Android or iPhone app marketing, your potential audience will hardly discover your app. Your perfect strategic marketing plan must start before your app’s actual launch.

You’re looking for “growth” hacks

Everyone finds short and effective hacks or smart tactics to stay on top for long-term. However, there is no such kind of things. Still you can do certain things to get a sustainable competitive advantage over your competitors to increase sales.

  • Become the top at understanding your customers or audience.
  • Do market research, interview your target users, understand as much as possible to find out what they search for in app and what drives them to download your mobile app.
  • Track to see which features and solutions users browse more so you can incorporate into your app.
  • You also need to beef up your marketing, from the pre-launch phase until after you release your app.
  • You need to continue creating buzz, by providing latest updates even when you reach the top of the charts. Otherwise, they may lose interest in the long run and, your app will be the first to go from their mobile phones.
  • Your app’s download figures shouldn’t be the sole basis of your success. It’s not necessary that if you’re getting tons of downloads, your app is being used. Users can uninstall or leave app if they don’t find relevant to their interest. High app abandonment figure can cause a problem on your hands.
  • Grow your mobile application and user retention by utilizing in-app messaging. These visual notifications are triggered by how users are using your app, helping direct them on what they should do next. This strategy can encourage your users to explore your app further, discover its unique features and even use it more often.

This can then improve your user retention and revenue.

Keep subscribing for latest updates from Rootsquare Technologies. We will share more tips about common mistakes to avoid when launching mobile app.


Source credit: What Things to Avoid When launching An App?

How Much Does it Cost to Make An Android & iPhone App in 2019 ? [with infograph]

Have you ever think how much Android or ios app development would cost?

Here we explain about the approximate costs of an Android app development or iPhone app development based on the figures for popular mobile apps as most of people know.

  • Globally, the number of smartphone users exceeds more than three billion in 2018, with Asia-Pacific accounting for over half of this number.
  • The world’s consumers will spend approx $94 billion on apps this year; more than three-quarters (76%) of these revenues will be generated by mobile games.
  • The most popular smartphone brands are Samsung with market shares of 27% and Apple is with 24%, respectively.

According to Global Mobile Market Report 2018, that number will be more than $107 billion in upcoming 2 years.

If you’ve ever thought about making your own app, then you’ve probably wondered, “How much does it cost to make an app in 2019?

In this post, we’ll show you how an Android or iPhone app development cost to make a clone for some of the top applications, i.e. Facebook, Whatsapp, Instagram, Ticktock, Zomato.  App complexity is another cost-related factor, which includes app developers (freelancer vs. agency) who build your app, and on which platform (iOS vs. Android) it’s going to be developed.

most popular apps chart in the world 2019

As indicated by SensorTower’s report, the applications appeared in the outline above were the most prominent applications a year ago by worldwide application downloads.

On the off chance that you need to make an application or hire mobile app developer to build an app, regardless of whether it’s for versatile or web, it may be helpful to consider these kinds of applications to furnish you with a structure. Since these applications contain certain highlights that are normal to a wide scope of applications, understanding the expenses of these highlights is essential to building up your very own application.

The following segment will show how to ascertain application costs, before going into more subtleties on real expenses.

So, Application development cost  would be depends on two factors:

  • Development Time
  •  Hourly Rate of Developer

How Much Does it Cost to Create an App?

App Cost = Development Time  X Hourly Rate

The basic approach to calculate application cost is simply as:

App Cost = (Time * Application Features) X Hourly Rate.

As each application have their own features list, so you can hire iOS app developer or android developer to specify them about your required features list that you want to implement or add in an App. So, time will be calculating accordingly and you can pay hourly or fix charges to mobile app development company in USA or app developer you hired.

Source Credit: How Much Does it Cost to Make An Android & iPhone App in 2019 ?