Apple's position
Where is the iMessage API documentation?
Apple's Messages documentation covers building iMessage apps and does not include a send endpoint. For a working API reference you need a third-party provider: Sendblue, Blooio and LoopMessage publish theirs openly, Blooio ships an OpenAPI specification, and Miss Blue keeps its reference behind a sign-in.
Documentation posture, August 2026
A gated API reference is itself a signal
It is a decision that you should be qualified before you are informed. Not disqualifying, but worth noticing — and an OpenAPI spec is worth more than a nicely designed docs site, because you can generate a client from it and diff it when it changes.
The five things to look up first
- The error table. If there is not one, the platform has not enumerated its failure modes. You specifically want "not on iMessage" distinguished from "rate limited" from "we are broken".
- Rate limits, in numbers. Per minute and per day, and whether exceeding them returns a 429 or silently queues. Silent queueing is worse.
- The full webhook payload plus the signing algorithm. Unsigned means unauthenticated in practice.
- The awkward endpoints — removing a reaction, group threads, number lookup. These reveal how deep the integration goes.
- A dated changelog. No changelog means you learn about breaking changes from your error rate.
Further reading
Go deeper
Provider documentation compared
What to look for in an iMessage API reference before you commit, which providers publish enough to evaluate without a sales call, and the specific endpoints that reveal how good the platform really is.
8 min readOperationsiMessage from Node.js
A working Node.js integration: a typed client, webhook verification with Express, retries that respect rate limits, and a send queue that will not get your line flagged.
12 min readStrategyApple's real Messages APIs
Apple publishes a lot of Messages documentation. None of it lets you send an iMessage to a phone number from a server. Here is what each framework really does.
9 min read