--- title: "API and Interface Design - Air Market" description: "When you are about to let other code depend on yours, the names and boundaries you choose now become hard to change later. This offers steady guidance at that moment: how to shape an API or split res…" canonical: "https://airmarket.ai/app/api-and-interface-design" --- [Air Market](/) / [Developer Tools](/category/devtools) / API and Interface Design Skill by [Addy Osmani](/@addyosmani) # API and Interface Design Draw clean lines between the parts of your system ## What this does When you are about to let other code depend on yours, the names and boundaries you choose now become hard to change later. This offers steady guidance at that moment: how to shape an API or split responsibilities so the pieces fit together sensibly. Reach for it whenever you catch yourself hesitating over where one part of your system should end and another begin. ### Top 3 things it does for you - Design a new REST or GraphQL endpoint - Set the type contract between modules - Work out where the frontend ends and the backend starts ## Information **API and Interface Design at a glance** | | | | --- | --- | | Kind | Skill | | Publisher | [Addy Osmani](/@addyosmani) | | Category | [Developer Tools](/category/devtools) | | Works with | Agent Skills - an open standard supported by 40+ agents | | Size | 15 KB | | Licence | MIT | | Repository | [addyosmani/agent-skills](https://github.com/addyosmani/agent-skills/tree/df1edb2e05487d0aa6d93c747141e0aed1187f25/skills/api-and-interface-design) | | GitHub stars | 114,337 (as of Nov 2026) | | Installs | 73,163, counted by skills.sh (Nov 2026) | ## Security report **Verified.** AIR scanned this exact version of API and Interface Design and flagged nothing. AIR's verdict: **safe**. **What API and Interface Design's check was run against** | | | | --- | --- | | Commit | df1edb2e05487d0aa6d93c747141e0aed1187f25 | | Content hash | a8fc6cf1022fa0804c73c268a4c09f1680ee186f846ca1a78c4e7f2841ee0e07 | | Files read | [Browse the files at this exact commit](https://github.com/addyosmani/agent-skills/blob/df1edb2e05487d0aa6d93c747141e0aed1187f25/skills/api-and-interface-design/SKILL.md) | A scan is named by the exact content it read, not by a version number. A different version is a different artifact, and nothing here applies to a version AIR has not scanned. [Read the full security report for API and Interface Design](/security/api-and-interface-design) ## About API and Interface Design Some code is written to be used by other code, and this is guidance for shaping exactly that: your APIs, your public interfaces, and the boundaries between the pieces of a system. Reach for it when you are creating REST or GraphQL endpoints, when you are defining type contracts between modules, or when you are working out where the boundary between frontend and backend should sit. The through-line is stability. Interfaces are treated as promises made to whoever builds against them, so the emphasis falls on choosing them deliberately rather than letting them emerge by accident. ## What's inside - SKILL.md - instructions ## Questions ### Is API and Interface Design safe to install? AIR scanned this exact version of API and Interface Design and flagged nothing. AIR's verdict: safe. The verdict is named by the content that was read, at commit df1edb2e0548, so it cannot drift onto a version nobody scanned. The full report is at https://airmarket.ai/security/api-and-interface-design. ### How do I install API and Interface Design? Open https://airmarket.ai/app/api-and-interface-design on Air Market and use the install action: Air Market hands Claude a prompt naming this exact skill, and Claude sets it up. Source, pinned to the exact commit this listing describes: https://github.com/addyosmani/agent-skills/tree/df1edb2e05487d0aa6d93c747141e0aed1187f25/skills/api-and-interface-design. Install from that link, not the branch. ## Related on Air Market - [More Developer Tools listings](/category/devtools) - [Everything by Addy Osmani](/@addyosmani) --- Canonical URL: