A unified reference for Solana program Interface Description Language (IDL) formats. IDLs describe the public interface of on-chain programs -- their instructions, accounts, types, events, errors, and constants -- enabling tooling to generate clients, documentation, and transaction builders automatically.

This first version of the specification is based on the anchor-lang-idl-spec and will serve as a framework-agnostic standard for all Solana IDLs.

Frameworks that generate IDLs conforming to this spec:

• Anchor -- Solana program framework maintained by Ottersec. Generates IDLs at build time via anchor build.

• Quasar -- Solana program framework maintained by Blueshift. Generates IDLs at build time via quasar build.

• Native or Pinocchio programs can also generate Codama IDLs via Codama macros. This Solana IDL spec can be converted to Codama IDLs if needed.

Anchor automatically generates Web3js clients for your program via anchor build.

Quasar automatically generates Js clients and Rust clients for your program via quasar build.

The Solana IDL can be converted easily into a Codama IDL and then be used for client generation.

Codama -- Generate typed clients from Solana IDL. Supports multiple target languages (TypeScript, Rust, Go, Python, etc.).

pnpm install codama
codama init
codama run --all

You can generate C# clients for your program via the Magic block sdk.

dotnet anchorgen -i idl/file.json -o src/ProgramCode.cs

Program Metadata -- Attach IDLs, security.txt, and other metadata to any Solana program via on-chain PDA accounts. Also offers multisig support.

# Upload an IDL to your program
npx @solana-program/program-metadata@latest write idl <program-id> ./idl.json

# Fetch an IDL from a deployed program
npx @solana-program/program-metadata@latest fetch idl <program-id> --output ./idl.json

Using the legacy IDL upload via the injected anchor code into anchor programs is deprecated for security reasons and you should move to use the new Program Metadata program.

Historical IDL -- Reconstruct the full version history of a Solana program's IDL from on-chain transactions. Supports both legacy Anchor IDL and Program Metadata formats.

npx tsx src/cli.ts <program-address> --rpc <rpc-url> --type both --dump-idls ./idls

idl-spec/
├── README.md                   # This file
├── CONTRIBUTING.md             # Contribution guidelines and RFC process
├── LICENSE                     # MIT license
├── schema/
│   └── v0.1.0.json             # JSON Schema for IDL validation
├── specs/
│   └── v0.1.0.md               # IDL spec v0.1.0
└── examples/
    └── counter.json            # Example IDL

Contributions are welcome. See CONTRIBUTING.md for full details.

• Spec changes go through the RFC process -- open an issue using the RFC template, allow at least 2 weeks for discussion, then submit a PR once accepted. For breaking changes lets do 4 weeks.
• Tooling additions, examples, and editorial fixes can be submitted as a standard pull request.

This project is licensed under the MIT License.