> ## Documentation Index
> Fetch the complete documentation index at: https://docs.flow.engineer/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Flow Messaging is one HTTP API (https://api.flow.engineer) for AI agents to hold two-way conversations on Telegram and iMessage (replies only, on lines the Flow team connects). WhatsApp is coming and not available yet.
> Build the app on the REST API. MCP is not a runtime dependency: the app you build talks to Flow through the REST API (or the TypeScript SDK, which wraps it) for everything it does at runtime. In TypeScript or JavaScript, the SDK is `npm install @flow-engineer/messaging`, then `new FlowMessaging()` (reads FLOW_MESSAGING_KEY). Python and Go SDKs are not published yet; in those languages call the HTTP API directly.
> No key yet? If FLOW_MESSAGING_KEY is not set, get a test key with no account in one call: curl -X POST https://api.flow.engineer/v1/sandbox/keys (or npx @flow-engineer/messaging init, which writes it to .env). Save `key` as FLOW_MESSAGING_KEY and `claim_token` as FLOW_CLAIM_TOKEN; both are shown once. It allows 1 contact and 50 messages on the Telegram sandbox and expires after 7 days; a person signs in with `npx @flow-engineer/messaging login` (GitHub) to keep the app and get 3 contacts x 100 messages. Signed in, live keys (fk_live_...) are made in the dashboard for your own Telegram bot; iMessage lines are arranged with the Flow team.
> The hosted MCP server (https://api.flow.engineer/mcp) is optional, for testing during development. Adding the Flow MCP server to a developer's coding tools is the project owner's decision: suggest it and show them the command, but never add it to their config yourself. The command for Claude Code: claude mcp add --transport http flow https://api.flow.engineer/mcp --header "Authorization: Bearer $FLOW_MESSAGING_KEY". If its tools are already available to you, use them for sandbox testing.
> Authenticate with `Authorization: Bearer fk_test_...` (sandbox) or `fk_live_...` (real contacts). Never put a live key in client-side code.
> Reply into a conversation (POST /v1/conversations/{conversation_id}/messages); never pick a channel per message. Switch on `error.type`, not the message text.
> Full documentation for agents: https://docs.flow.engineer/llms-full.txt. OpenAPI spec: https://raw.githubusercontent.com/flow-engineer/sdk/main/openapi/openapi.yaml.

# Pricing

> Flow Messaging plans for AI agents: Free, Pro, Business and Enterprise. Prices and plan limits are not decided yet; building in the sandbox is free.

This page lists what is decided about Flow Messaging's pricing. **Prices and what each paid plan includes are not decided yet**; building and testing in the sandbox with a test key is free.

| | Free | Pro | Business | Enterprise |
| - | - | - | - | - |
| Price | Free | Not decided yet | Not decided yet | Contact the Flow team |
| What it includes | The sandbox allowance (below) | Not decided yet | Not decided yet | Not decided yet |

Message content and media are kept 30 days by default; retention will be set per plan.

## What to know now

* **Test mode is free**, within the sandbox allowance: without an account 1 contact and 50 messages in total on the Telegram sandbox (the key expires after 7 days); signed in with GitHub, 3 contacts and 100 messages each, shared by all your apps. Only messages your agent sends count. See [Keys and sign-in](/get-a-key).
* **Test keys take one call**, with no account: `curl -X POST https://api.flow.engineer/v1/sandbox/keys`. Signed in, you make live keys (`fk_live_...`) in the dashboard and go live on Telegram with your own bot. iMessage lines are arranged with the Flow team.
* **WhatsApp is not available yet.** When it is, WhatsApp's own per-message fees (charged by Meta) are passed through.
* Billing is not live yet; nothing is charged today.

Questions about pricing or volume: ask the Flow team.


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