# I/O JMAP [](https://docs.rs/io-jmap/latest/io_jmap) [](https://matrix.to/#/#pimalaya:matrix.org) [](https://fosstodon.org/@pimalaya)
JMAP client library for Rust
This library is composed of 3 feature-gated layers:
- Low-level **I/O-free** coroutines: no_std-compatible state machines containing the whole JMAP logic, usable anywhere
- Mid-level **light client**: a standard, blocking client wrapping a stream you opened yourself
- High-level **full client**: the light client plus TCP connections and TLS negotiations handled for you
## Table of contents
- [Features](#features)
- [RFC coverage](#rfc-coverage)
- [Usage](#usage)
- [Examples](#examples)
- [AI disclosure](#ai-disclosure)
- [License](#license)
- [Social](#social)
- [Contributing](#contributing)
- [Sponsoring](#sponsoring)
## Features
- **Session discovery**: resolves the JMAP session from a base URL or the well-known endpoint, surfacing redirects to the caller instead of following them.
- **Core protocol**: batched method calls, generic get, set, query and changes flows, blob upload and download.
- **Push notifications**: push subscription management and the streaming Event Source channel, yielding one state change per push frame with cooperative shutdown.
- **Mail**: mailboxes, emails, threads, identities, email submissions and vacation responses.
- **Contacts**: address books and contact cards, the JSContact payload kept as raw JSON.
- Full standard, blocking client with **TLS** support:
- [Rustls](https://crates.io/crates/rustls) with ring crypto (requires `rustls-ring` feature, enabled by default)
- [Rustls](https://crates.io/crates/rustls) with aws crypto (requires `rustls-aws` feature)
- [Native TLS](https://crates.io/crates/native-tls) (requires `native-tls` feature)
> [!TIP]
> I/O JMAP is written in [Rust](https://www.rust-lang.org/) and uses [cargo features](https://doc.rust-lang.org/cargo/reference/features.html) to gate the client layers. The default feature set is declared in [Cargo.toml](./Cargo.toml) or on [docs.rs](https://docs.rs/crate/io-jmap/latest/features).
## RFC coverage
| RFC | What is covered |
|--------|---------------------------------------------------------------------------------------------------------------------------------------------|
| [8620] | JMAP core: session discovery, batched API requests, generic get, set, query and changes methods, blobs, push (Event Source, PushSubscription) |
| [8621] | JMAP for Mail: Mailbox, Email, Thread, Identity, EmailSubmission, VacationResponse |
| [9610] | JMAP for Contacts: AddressBook, ContactCard (JSContact payload kept as raw JSON) |
[8620]: https://www.rfc-editor.org/rfc/rfc8620
[8621]: https://www.rfc-editor.org/rfc/rfc8621
[9610]: https://www.rfc-editor.org/rfc/rfc9610
## Usage
The whole API is documented on [docs.rs](https://docs.rs/io-jmap/latest/io_jmap), including runnable snippets for every coroutine and client.
## Examples
Complete runnable programs live in [./examples](./examples); the tests also demonstrate real usage against live JMAP servers.
## AI disclosure
This project is developed with AI assistance. This section documents how, so users and downstream packagers can make informed decisions.
- **Tools**: Claude Code (Anthropic), invoked locally with a persistent project-scoped memory and a small set of repo-specific rules.
- **Used for**: Refactors, mechanical multi-file edits, boilerplate (feature gates, error enums, derive macros, trait impls), test scaffolding, doc polish, exploratory design conversations.
- **Not used for**: Engineering, critical code, git manipulation (commit, merge, rebase…), real-world tests.
- **Verification**: Every AI-assisted change is read, compiled, tested, and formatted before commit. Behavioural correctness is verified against the relevant RFC or upstream spec, not assumed from the model output. Tests are never adjusted to fit AI-generated code; the code is adjusted to fit correct behaviour.
- **Limitations**: AI models occasionally produce code that compiles and passes tests but is subtly wrong. The verification workflow catches most of this; it does not catch all of it. Bug reports are welcome and taken seriously.
- **Last reviewed**: 15/07/2026
## License
This project is licensed under either of:
- [MIT license](LICENSE-MIT)
- [Apache License, Version 2.0](LICENSE-APACHE)
at your option.
## Social
- Chat on [Matrix](https://matrix.to/#/#pimalaya:matrix.org)
- News on [Mastodon](https://fosstodon.org/@pimalaya) or [RSS](https://fosstodon.org/@pimalaya.rss)
- Mail at [pimalaya.org@posteo.net](mailto:pimalaya.org@posteo.net)
## Contributing
Contributions are welcome: start with [CONTRIBUTING.md](./CONTRIBUTING.md), which opens with the Pimalaya-wide guides to read first.
## Sponsoring
[](https://nlnet.nl/)
Special thanks to the [NLnet foundation](https://nlnet.nl/) and the [European Commission](https://www.ngi.eu/) that have been financially supporting the project for years:
- 2022 → 2023: [NGI Assure](https://nlnet.nl/project/Himalaya/)
- 2023 → 2024: [NGI Zero Entrust](https://nlnet.nl/project/Pimalaya/)
- 2024 → 2026: [NGI Zero Core](https://nlnet.nl/project/Pimalaya-PIM/)
- *2027 in preparation…*
If you appreciate the project, feel free to donate using one of the following providers:
[](https://github.com/sponsors/soywod)
[](https://ko-fi.com/soywod)
[](https://www.buymeacoffee.com/soywod)
[](https://liberapay.com/soywod)
[](https://thanks.dev/soywod)
[](https://www.paypal.com/paypalme/soywod)