oasdiff

Detect breaking changes, generate changelogs, diff, and validate OpenAPI specs.

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What it can do

    What data it sees

    Do you need an account

    No: the server works without sign-in

    Detect breaking changes, generate changelogs, diff, and validate OpenAPI specs.

    How to connect

    How to connect oasdiff to Claude

    The server address to paste into Claude settings:

    https://api.oasdiff.com/mcp

    1. Open Claude (claude.ai or the desktop app).
    2. Go to Settings → Connectors.
    3. Click Add custom connector.
    4. Paste the server address copied below into Remote MCP server URL and click Add.
    5. In a chat, click + → Connectors and switch the new connector on.

    Custom connectors are available on Free, Pro, Max, Team and Enterprise plans (Free is limited to one). On Team and Enterprise an organization Owner adds the connector first under Organization settings → Connectors.

    Authorization

    After you click Add, a sign-in window for the service opens. Sign in with your own account and approve access. Claude never sees your password.

    How to connect oasdiff to ChatGPT

    The server address to paste into ChatGPT settings:

    https://api.oasdiff.com/mcp

    1. Open ChatGPT in a browser (chatgpt.com). A Plus, Pro, Business, Enterprise or Edu plan is required.
    2. Turn on developer mode once: Settings → Apps → Advanced settings → Developer mode.
    3. Open Settings → Connectors and click Create.
    4. Fill in the form: Name (anything), Description (one line about what the service does), MCP server URL (copy it below).
    5. Under Authentication choose OAuth if the service requires sign-in, otherwise None. Click Create.
    6. In a new chat open + → Apps/Connectors and enable the connector.

    OpenAI has renamed this section before (Connectors → Apps/Plugins). If the label differs, search settings for "developer mode". On Business/Enterprise workspaces an admin must allow custom connectors first.

    Authorization

    On first use ChatGPT opens the service's sign-in window. Sign in and approve access.

    How to connect oasdiff to Cursor

    The server address to paste into Cursor settings:

    https://api.oasdiff.com/mcp

    Fastest: click Open in Cursor below and confirm the prompt.

    Manually:

    1. In Cursor open Settings → Cursor Settings → MCP and click Add new global MCP server.
    2. Paste the JSON copied below into ~/.cursor/mcp.json (per project: .cursor/mcp.json in the repo root).
    3. Save the file. The server appears in the MCP list; authorize it there if asked.

    Authorization

    If the service needs sign-in, an authorize button appears next to the server in the MCP list.

    Server tool list (4)

    Raw names from tools/list. Only developers need these.

    oasdiff_breaking_changesDetect breaking API changes between two OpenAPI specifications. Pass the base (old) and revision (new) specs as YAML or JSON; returns the breaking and warning-level changes. Use this when the question is whether an API change breaks existing clients. Use oasdiff_changelog instead to list every change including non-breaking and informational ones, oasdiff_diff for the raw added/removed/modified structure, or oasdiff_validate to check a single spec rather than compare two. Both specs must be valid, self-contained OpenAPI (external $ref URLs or files are not resolved).
    oasdiff_changelogProduce a full changelog of every detected change between two OpenAPI specifications (base vs revision), down to informational changes. Pass both specs as YAML or JSON. Use this when you want the complete set of changes at every severity. Use oasdiff_breaking_changes instead when you only care whether the change is breaking (less noise), or oasdiff_diff for the raw structural diff without a backward-compatibility judgment. Both specs must be valid, self-contained OpenAPI (external $ref URLs or files are not resolved).
    oasdiff_diffShow the structural diff between two OpenAPI specifications (base vs revision): what was added, removed, or modified. Pass both specs as YAML or JSON. Use this when you want the raw structural changes rather than a backward-compatibility verdict. Use oasdiff_breaking_changes to judge whether changes break clients, or oasdiff_changelog for a severity-classified changelog. Both specs must be valid, self-contained OpenAPI (external $ref URLs or files are not resolved).
    oasdiff_validateValidate a single OpenAPI specification against the OpenAPI and JSON Schema rules. Pass the spec as YAML or JSON; returns the findings (empty when the spec is valid). Use this when you have one spec and want to check it is well-formed. For comparing two specs, use oasdiff_breaking_changes, oasdiff_changelog, or oasdiff_diff instead. The spec must be self-contained (external $ref URLs or files are not resolved).