WhatsApp iMessage Telegram

Three chat apps. One API.

Typed events in, typed messages out. Flow handles each channel's webhooks and rules.

Get an API key Read the docs

Fernhill Bakeryonline

any sourdough left today?9:14 ✓✓

Yes, 6 loaves. Want me to hold one until 6pm?9:14

Hold oneNo thanks

Hold one9:14 ✓✓

Held under your name. See you later!9:14

👍

Message

What it does

The channel work, done once.
Your code just replies.

One API, three channels

Reply into a conversation. The same code answers everywhere.

Signed webhooks, idempotent sends

Signed, ordered deliveries with retries. A repeated send goes out once.

Rich messages, not just text

Buttons, media, voice notes, reactions, typing and read receipts.

Each channel's rules, handled

WhatsApp's 24-hour window, templates and who may be messaged first.

Start in one call

A key, then a reply.

TypeScript and Python SDKs, or plain REST
Events by webhook, live stream or polling
Hosted senders: shared sandbox, then your own
MCP server and llms.txt for coding agents
Telegram sandbox key in one call
Flow is a WhatsApp Tech Provider

terminal

# 1. a test key in one call, no account
curl -X POST https://api.flow.engineer/v1/sandbox/keys

# 2. save "key" as FLOW_MESSAGING_KEY (shown once)
# 3. open senders[].address.link on your phone

# 4. reply from your agent
npm install @flow-engineer/messaging
pip install flow-messaging

Put your agent where people already text.

Building in the sandbox is free.