Voice calling plays a crucial role in personal and professional communication. Be it a friendly conversation among classmates or a business deal between companies – voice calling has been the most easy, convenient, and affordable way to communicate for decades. Thus, communication corporations and developers have brought in innovative ways to integrate their Application Programming Interfaces (APIs) and invent newer ways of voice communication. Voice API is referred to as a tool that allows software developers to integrate calling features using an Application Programming Interface (API). Developers build a chat app with voice functionality and Voice APIs let these apps make and receive phone calls acting as a bridge to PSTN (Public Switched Telephone Network). These voice APIs are highly flexible for developers as they simplify the app's design and development by saving money and time. APIs are considered to be the most simplified way to connect any infrastructure through cloud-native app development, wherein they also permit the developers to share their data with other external sources. The four main standards of measuring a good Voice Chat API:  API features : Every API may have a unique feature or offering. However, to build voice chat for android, iOS & the web, developers need to analyze their requirements. The basic agenda is to integrate a voice API that allows to develop a calling functionality that covers all types of users on any device, over numerous networks, anywhere in the world. Popularity :A competent Voice chat API gives developers programmatic control over calls and enables them to build call logic and VoIP functionality. But the level of popularity and the number of users can only indicate the efficiency of a voice API. Price :  Affordability is also a key factor that distinguishes the best voice API providers. Live voice chat APIs can offer a lot of functionality, but they are only accessible by enterprises if they are cost-effective. Ease of Use : Developers can integrate voice calling APIs with CRM, Helpdesk, Apps, and many other mobile and web platforms, but this integration needs to be easy and adaptable. Therefore, ensure ease of use while reviewing and selecting the best voice calling API for app developers. CONTUS MirrorFly Voice Call API Plivo API Vonage API Twilio API EnableX API MessageBird API Sinch API Siri API Google Cloud Speech API Viber API Visit Website : MirrorFly.com CONTUS MirrorFly voice calling solution is a customizable communication APIs and SDKs. It allows enterprises to develop and integrate easy communication systems on Android, iOS, and Web applications. CONTUS MirrorFly voice chat APIs have hundreds of collaboration features with scalable options that support billion + concurrent users to communicate at the same time.   Voice API Features 100% Customizable Unlimited Calling  SIP/VoIP Calling Voice Recording Call Queuing & Routing Audio Encryption  Multi-User Interface Call Barging Popularity - Extremely popular with Billion + concurrent users Price - One time license cost (Custom Quotes) Ease of Use : Very Easy Visit Website : Plivo.com Plivo is a cloud communication platform that offers voice API solutions for enterprises to build powerful voice call workflows and scale business communications. pilvo’s APIs and SDKs can be instantly integrated into voice chat applications. Plivo has over 1600 local carrier networks delivering reliable connectivity in over 195 countries. Voice API Features Conference Call Voice Alerts & Surveys Voicemail Transcription Scalable Cloud IVR Call forwarding SIP Gateway & Devices Dynamic Caller ID Multi-Party Calls Popularity - 100,000 businesses Price - With pay-as-you-go pricing with free but limited usage. Ease of Use :  Easy Visit Website : Vonage.com Vonage APIs enables enterprises to build best-in-class communications solutions. Vonage APIs are structured on a global platform and offer an all-inclusive suite of communications channels and expert support. Vonage allows developers and tech enterprises to construct and launch communication services from scratch. Voice API Features Call Recording & Analytics  Unlimited US Calls Carrier-Grade Performance Support Team & End-To-End Assistance Solution Consulting & Project Scoping Popularity - 1.1 billion subscribers Price - Prices starting from € 0.0040 /minute Global IP Call Ease of Use :  Easy Visit Wesite : Twilio.com Twilio's programmable voice API offering calling facilities across the world. With REST API developers can integrate voice chat functionality that allows users to make, receive, monitor, and modify calls along with query metadata about calls that were created.     Voice API Features Set Up SIP  Natural Language Understanding  Insights & Reporting Retrieve Call Logs Modify In-Progress Calls Detect Answering Machines Popularity - 1 million developers Price - Free with limited usage Ease of Use :  Easy EnableX API is a voice messaging platform that offers developers to embed real-time, high-quality, and interactive voice calling on applications built for Web, iOS, and Android applications. Voice API Features Make calls to a SIP/PSTN using REST API Receive calls on EnableX Voice server  Use Webhook & Initiate Additional Actions Bridge & Broadcast Calls  Play Custom IVR Collect User Response Over DTMF  Send Text-To-Speech Messages In 40 Languages Popularity - Significantly Popular Price - Starting at $0.0024/Min to receive and $0.0127/Min to make a call Ease of Use :  Easy MessageBird is a communications platform-as-a-service (CPaaS) company. MessageBird reforms and streamlines the overcomplicated space of customer communication. MessageBird’s Voice Messaging API permits users to transform texts into voice messages to any country. Voice API Features Make & Receive Calls Decentralised Call Centres Use of Interactive Voice Response Cloud Telephony  Text to Speech Popularity - 15,000 users Price - Free and varying paid plans from $50 to customized quotes Ease of Use :  Easy Sinch is a company that makes all types of communications APIs. Sinch provides developers an easy and effective way to add voice chat functionality into the apps. It lets developers integrate voice messaging into any type of platform in minutes with a few lines of code  Voice API Features Conference calling Call recording Answering machine detection IVR menus Voice-based IVR (Open Beta) Recorded prompts Text-to-speech Popularity - 5 billion consumers Price - Customised quotes for inbound calls & outbound calls starting at *$0.0244 Ease of Use :  Easy Siri API or a SiriKit is the intended UI framework that enables developers to implement app extensions that integrate the chat system. Developers can integrate voice assistant functionality into third-party apps that they have built and send voice messages on calls or authenticated transactions. Voice API Features Add Intelligent Voice Assistance  Offer AI Assistance Replies Smart Answers to Users Make Voice Queries Perform Voice-Related Tasks Popularity - 3 million users Price - Free and varying paid plans from $4.99 to $99.99 per month Ease of Use :  Easy Google Cloud Speech APIs allows easy integration of Google speech recognition technologies into applications and messaging systems built by developers. With Google Cloud Speech APIs, developers can translate from audio to text and apply powerful neural network models. Voice API Features Convert Audio to Text Messages Uses Neural Network Models Recognizes 80 Plus Languages & Variants Supports A Global User Base Popularity - Millions of users Price - Free but limited usage Ease of Use :  Easy Viber REST API is a bot platform that is open and free for usage. Programmers create bots in an ecosystem that allows users to share text, voice, and video messages with other Viber users available in the contacts. Viber REST API can also be used on third-party websites and social media channels using a deep-link.  Voice API Features Smart Notifications Shift Between Conversations Block / Unblock Contacts  Turn off Notifications & Status Change Wi-Fi Sleep Policy Popularity - 260 million monthly users Price - Free  Ease of Use :  Easy However, the above provided list of voice chat API and SDK providers are the few top one's from the ocean of many. Still have tried to cover all the details of them to get you a better clarity with the outcome. Now, you must have got a view as to who are the approachable voice chat API providers in the market to build your voice calling app.  Now, the ball is in your court and as these voice API are meant especially for developers, it’s up to you as to what to go for to build your voice chat app - something from scratch or a ready-made voice chat APIs. Whatever be the case, the decision is yours, and we are here to support you with more clarity and guidance if you ever need it. Good Luck!  Growth Hacker & Product Markter