The SDK: @leumas/solidity
One package, in the Leumas monorepo, that the site is built from. The REST lane under /api/remix serves the library and, with a key, compiles for you.
In the browser
compile({ sources }) runs the pinned solc in a Web Worker loaded from /remix-solc/<version>/soljson.js. describeAbi, encodeCall, decodeResult and decodeError cover the codec. discoverProviders, connect, deploy, read, write and watchEvents cover the wallet, on viem. verify compares bytecode.
The REST lane
GET /api/remix/status, /library and /contracts/:slug are free. POST /api/remix/verify is free and rate-limited signed out. POST /api/remix/compile is the SDK door: an API key with the remix scope, or a member with remix.keys, metered against a monthly ceiling. Workspaces are member routes.
What is not in the SDK
A signer. The adapter and the MCP tool expose compile, ABI, encode and verify and nothing that signs or sends. That is a rule of this site, and the public guard greps for a private key on every build.
Publishing
The package is not on the public npm registry yet; this page will carry the install command when it is.