Free Communication APIs — ranked by value

Email, SMS, push, realtime

Scores rate free-tier value on a 1–10 scale. How scores work →

Twilio Communication API key Programmable SMS, voice, WhatsApp, and verification APIs that power messaging for apps at any scale. Trial credit
SendGrid Communication API key Cloud-based transactional and marketing email API with templates, analytics, and high deliverability. 60/day
Resend Communication API key Developer-first transactional email API with React Email support and a generous free tier. 100 msg/day
Postmark Communication Token Fast transactional email API focused on deliverability, with detailed delivery and bounce tracking. 100 msg/mo
Mailgun Communication API key Transactional and bulk email API with powerful routing, validation, and inbound parsing. 100 msg/day
Pusher Channels Communication API key Hosted pub/sub WebSocket API for adding realtime features like live updates and chat to apps. 200k msg/day
OneSignal Communication API key Customer engagement platform with APIs for push notifications, email, SMS, and in-app messaging. 10k/mo
Vonage Communication API key Communications APIs (formerly Nexmo) for SMS, voice, video, WhatsApp, and number verification. Trial credit
MessageBird (Bird) Communication API key Omnichannel CPaaS for SMS, voice, WhatsApp, email, and live chat through a unified API. Trial credit
Courier Communication API key Notification orchestration API that routes messages across email, SMS, push, and chat from one call. 10k/mo
Knock Communication API key Notifications-as-a-service API for cross-channel workflows, preferences, and in-app feeds. 10k/mo
Telnyx Communication API key Carrier-grade APIs for SMS, voice, programmable numbers, and verification on a private IP network. Trial credit
Plivo Communication API key Cloud communications platform offering SMS, voice, and WhatsApp APIs with global coverage. Trial credit
Sinch Communication API key Global CPaaS for SMS, voice, video, WhatsApp, and verification across mobile carriers worldwide. Trial credit
Infobip Communication API key Omnichannel communications API supporting SMS, WhatsApp, voice, email, and 15+ channels. Trial credit
Bandwidth Communication API key Tier-1 carrier APIs for SMS/MMS, voice, 911 access, and phone number provisioning in the US. Trial credit
Brevo Communication API key All-in-one marketing platform (formerly Sendinblue) with APIs for transactional email and SMS. 300 msg/day
Mailjet Communication API key Transactional and marketing email API with collaborative templating in MJML or HTML. 6k msg/mo
Amazon SES Communication API key Low-cost, scalable transactional and bulk email sending service from AWS with SMTP and API access. 3k msg/mo
Loops Communication API key Email platform for SaaS with a simple API for transactional and lifecycle email campaigns. Free tier
EmailJS Communication API key Send emails directly from client-side JavaScript without running your own backend server. 200 msg/mo
Stream Chat Communication Token In-app chat and messaging API with SDKs, moderation, and scalable realtime infrastructure. Free tier
Sendbird Communication Token Chat, calls, and live-streaming APIs for embedding realtime conversations and AI agents in apps. Free developer tier: up
PubNub Communication API key Realtime messaging and pub/sub API for chat, presence, live updates, and IoT signaling. 200/mo
Ably Communication API key Realtime experience platform with pub/sub messaging, presence, and data sync over WebSockets. 6/mo
Liveblocks Communication API key Realtime collaboration API for multiplayer presence, comments, and notifications in apps. Free tier
Novu Communication API key Open-source notification infrastructure API for email, SMS, push, chat, and in-app feeds. 30k/mo
Agora Communication Token Realtime voice, video, and interactive live-streaming APIs with global low-latency delivery. 10k/mo
Daily Communication API key WebRTC video and audio API for embedding calls, plus realtime infrastructure for voice AI agents. 10k/mo
LiveKit Communication Token Open-source WebRTC platform and APIs for building realtime voice, video, and AI agents. 50/mo
Vapi Communication API key Voice AI platform with an API to build, test, and deploy conversational phone agents in minutes. Trial minutes
Retell AI Communication API key API for building production-ready conversational voice AI agents for inbound and outbound calls. Trial minutes
Telegram Bot API Communication Token Free HTTP API for building bots that send and receive messages on Telegram. 30 msg/sec
WhatsApp Cloud API Communication Token Meta-hosted API for sending and receiving WhatsApp Business messages, templates, and media. 1k/mo
Slack API Communication OAuth APIs and webhooks for posting messages, building bots, and integrating apps into Slack workspaces. 3/min
Discord API Communication Token API and gateway for building bots, sending messages, and integrating apps into Discord servers. 50 req/sec
ClickSend Communication API key Multichannel API for SMS, MMS, voice, email, and even physical post from a single account. Trial credit