Arti 2.1.0 released, advances relay and RPC development in Rust

Arti is our ongoing project to create a next-generation Tor implementation in Rust," and "We're happy to announce the latest release, Arti 2.1.0." The Tor Project's Arti team, in a blog post by gabi on March 3, 2026, frames this release around developer-focused engineering: relay support, RPC development, and infrastructure changes that prepare the codebase for broader testing.

"This release contains a lot of behind-the-scenes work on relay support and on RPC development." The post is explicit that "While Arti still cannot run as a relay, we are making good progress, and we think it will soon be ready for Arti developers to test it as a middle relay." That sets a clear short-term expectation: maintainers are moving relay code toward a developer test window rather than flipping a production-ready relay switch.

Configuration changes arrive as a sweeping internal migration. "Additionally, we have overhauled all of Arti's configuration to use a new, `derive-deftly`-based approach." The team adds, "We believe this will make defining new configuration types easier, saving us development time in the long run." For anyone extending Arti's configuration types or maintaining forks, the derive-deftly migration is the concrete change to inspect in PRs and the CHANGELOG.

The release also touches toolchain and maintenance requirements. "This release also contains a number of bugfixes, cleanups, as well as improvements to our CI infrastructure," and "Finally, Arti 2.1.0 increases our MSRV (Minimum Supported Rust Version) to 1.89.0, in accordance with our MSRV policy." Raising the MSRV to 1.89.0 is a policy-driven compatibility decision developers and CI pipelines will need to accommodate.

For the low-level details that matter to integrators, the team points readers to the project's notes: "For full details on what we've done, including API changes, and for information about many more minor and less-visible changes, please see the CHANGELOG." Usage pointers are also explicit: "For more information on using Arti, see our top-level README, and the documentation for the `arti` binary." The blog does not enumerate RPC wire formats, specific API signatures, or bug IDs, so the CHANGELOG and repository commits hold the next layer of technical detail.

The post closes in community mode, thanking contributors and sponsors: "Thanks to everybody who's contributed to this release, including Niel Duysters, Nihal, Nuhiat-Arefin, Robert Bartlensky, carti-it, hjrgrn, moumenalaoui, robertb, and sjcobb!" The blog, tagged announcements and releases and featuring social buttons labeled Copy link, Facebook, Twitter/X, Mastodon, Bluesky, also includes a moderated comments area with guidance: "We encourage respectful, on-topic comments. Comments that violate our Code of Conduct will be deleted."

Arti 2.1.0 reads as an engineering checkpoint more than a feature drop: it advances relay code and RPC scaffolding, moves configuration to derive-deftly, and formalizes Rust 1.89.0 as the supported baseline. Expect developer testing of middle-relay functionality to be the practical next milestone, with the CHANGELOG as the primary source for any API or migration work.