What kind of APIs does this MCP handle?

It handles two major types of API contracts: RESTful APIs using OpenAPI specifications, and modern graph APIs using GraphQL SDL.

Is this useful for version control?

Yes. It doesn't just show differences; it analyzes those differences to recommend whether your version bump should be MAJOR, MINOR, or PATCH.

Do I need to provide both schemas to use it?

Yes. The core function requires comparing two versions—the existing (base) contract and the proposed (target) contract—to detect changes.

Can I use this with my existing CI/CD pipeline?

While it's a capability for your AI client, you can integrate the logic into your workflow by having your agent run the comparison step before merging code.

What is a breaking change?

A breaking change is any modification that will cause existing client code to fail when they try to use the updated API contract.

What types of API contracts can I compare?

You can compare OpenAPI specifications and GraphQL Schema Definition Language (SDL) strings.

How does the capability recommend a version bump?

The evaluate_version_bump capability analyzes detected changes. A MAJOR bump is recommended for breaking changes, MINOR for additive changes, and PATCH for informational updates.

Can I detect type narrowing in OpenAPI?

Yes, diff_openapi identifies type narrowing (e.g., changing a string to a specific regex pattern) as a breaking change.

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Connect API Contract Diff Checker to ChatGPT and Claude

Set it up once and it works in ChatGPT, Claude, Cursor, and any other client you love. It all runs safely in the background, so you can relax and focus on what really matters. Catch breaking schema changes before they hit production.

Ask AI about this Connector

Developed, maintained, and hosted by Vinkius.

MCP VERIFIED · PRODUCTION READY · VINKIUS GUARANTEED

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Works with modern AI clients that support MCP, including ChatGPT, Claude, Cursor, and more.

Your AI does the work. We keep it safe and sound.

No other AI tool gives you this. Your workflow runs in the client you already love, your account stays protected, and you decide what the agent can and cannot do. It is the whole reason to make the switch.

Each Connector lives inside our infrastructure, the same place where your workflow runs. The three things below are already part of it, working quietly in the background so you never have to think about them. Nothing to add, nothing to set up, nothing to worry about.

V8 Isolate01

Each Connector runs inside its own sealed environment.

Each Connector runs inside its own sealed V8 runtime — no access to your files, your system, or other servers. A Connector never sees past its own request.

Kill Switch02

One switch stops every agent. Instantly.

One action deactivates every Connector, revokes every token, and ends every session at once. AI Governance keeps the record.

FinOps per User03

Spending limits that pause instead of surprise.

Every user keeps their own connections and credentials, isolated from everyone else. Anything that would cross your spending limit is held for your approval, not billed.

Three controls, built into the layer your AI connects through.

Curated set · 3 capabilities

We ship only the actions that matter.

Capability set01 / 01

01-03

3 capabilities in this set.

Part of 3 available through API Contract Diff Checker.

01
Diff graphql
Compares two GraphQL Schema Definition Language (SDL) strings to identify breaking and additive changes in your schema.
02
Diff openapi
Detects structural differences and compatibility impacts between two OpenAPI specification documents for REST APIs.
03
Evaluate version bump
Analyzes a collection of identified schema changes to recommend the appropriate Semantic Versioning increment (MAJOR, MINOR, or PATCH).

Real work

What teams actually run

Updating a User Endpoint

You removed the old /user/legacy endpoint. The MCP flags this removal as a breaking change.

Adding New Fields

A client needs a new email field. The MCP confirms this is an additive change, not a breaking one.

Migrating API Standards

You are moving from an older OpenAPI version to a new one. The MCP highlights all structural differences between the two specs.

Release Cycle Management

After finding several changes, the MCP analyzes the overall impact and recommends a MAJOR version bump.

One connector, every AI

API Contract Diff Checker works with the most popular AI clients.

These are the most popular clients, each with a step-by-step guide: one link, set up once, with governance and visibility built in. And because everything runs on the MCP standard, the same connection also works in any other compatible client — nothing to rebuild.

Building your own app? The connector is yours to use.

You don't need a client to put API Contract Diff Checker to work: the same hosted connection plugs into your own applications and agent code, with the same governance on every request. Build with it, chat with it — one connection for both.

Observed, not estimated

641ms average. Fast in production.

API Contract Diff Checker is checked daily against the live service.

Daily averagePeak 846ms

Oct 7Today

Fastest day: 549ms
Slowest day: 846ms
14-day trend: Slowing+11%

Connect your client

One URL. Every client.

Activate the Connector, copy your link, and paste it into the client you already use. 3 capabilities arrive ready to run.

Preview access · not provider authentication

The vk_preview_* token belongs to Vinkius preview infrastructure. It lets Claude discover and display the capabilities of API Contract Diff Checker, so you can see the experience inside your AI.

It does not authenticate your account with API Contract Diff Checker. Actions requiring credentials or live account data may not run until you activate the Connector and authorize the service.

API Contract Diff Checker Connector

You're all set. Choose your MCP client and follow the setup instructions.

Connector linkhttps://edge.vinkius.com/vk_preview_YNoFUtgqNHWnECjvlVZlbBc74OvhGVwRY5w7zSGv/mcp

Claude Desktop

Follow the steps below to connect in seconds.

1In Claude Desktop, open Settings → Connectors.
2Click “Add custom connector” and paste the connector link above as the remote MCP server URL.
3Click Add and start a new chat — API Contract Diff Checker capabilities are ready to use.

Configuration · claude_desktop_config.jsonCopy

{
  "mcpServers": {
    "api-contract-diff-checker-mcp": {
      "url": "https://edge.vinkius.com/vk_preview_YNoFUtgqNHWnECjvlVZlbBc74OvhGVwRY5w7zSGv/mcp"
    }
  }
}

Claude
ChatGPT
Cursor
VS Code
Windsurf
Claude Code
JetBrains
Cline

Step-by-step instructions for each client are in the guide. How to connect

Guided setup for Claude? Set up API Contract Diff Checker in Claude and other AIs

See all the AI clients this connector works with ↑

Who it's for

Built for the work API Contract Diff Checker owners hand off.

This MCP is essential for backend engineers, API architects, and DevOps teams. If your job involves maintaining or updating a public-facing API, you need this capability. It lets you prove that your changes won't break existing client integrations.

01
Backend Engineer
Use it to validate local schema changes before submitting a pull request.
02
API Architect
Use it to compare version contracts across different services to ensure compatibility.
03
DevOps Engineer
Use it to automate pre-deployment checks, preventing runtime failures caused by schema drift.

FAQ

Questions API Contract Diff Checker owners ask.

01
What kind of APIs does this MCP handle?
It handles two major types of API contracts: RESTful APIs using OpenAPI specifications, and modern graph APIs using GraphQL SDL.
02
Is this useful for version control?
Yes. It doesn't just show differences; it analyzes those differences to recommend whether your version bump should be MAJOR, MINOR, or PATCH.
03
Do I need to provide both schemas to use it?
Yes. The core function requires comparing two versions—the existing (base) contract and the proposed (target) contract—to detect changes.
04
Can I use this with my existing CI/CD pipeline?
While it's a capability for your AI client, you can integrate the logic into your workflow by having your agent run the comparison step before merging code.
05
What is a breaking change?
A breaking change is any modification that will cause existing client code to fail when they try to use the updated API contract.
06
What types of API contracts can I compare?
You can compare OpenAPI specifications and GraphQL Schema Definition Language (SDL) strings.
07
How does the capability recommend a version bump?
The evaluate_version_bump capability analyzes detected changes. A MAJOR bump is recommended for breaking changes, MINOR for additive changes, and PATCH for informational updates.
08
Can I detect type narrowing in OpenAPI?
Yes, diff_openapi identifies type narrowing (e.g., changing a string to a specific regex pattern) as a breaking change.

Explore

More in Developer Tools

Connect API Contract Diff Checker to Claude, Cursor, ChatGPT & more

Your AI does the work. We keep it safe and sound.

Each Connector runs inside its own sealed environment.

One switch stops every agent. Instantly.

Spending limits that pause instead of surprise.

We ship only the actions that matter.

01-03

Diff graphql

Diff openapi

Evaluate version bump

What teams actually run

Updating a User Endpoint

Adding New Fields

Migrating API Standards

Release Cycle Management

Building your own app? The connector is yours to use.

API Contract Diff Checker Connector

Claude Desktop

Backend Engineer

API Architect

DevOps Engineer

What kind of APIs does this MCP handle?

Is this useful for version control?

Do I need to provide both schemas to use it?

Can I use this with my existing CI/CD pipeline?

What is a breaking change?

What types of API contracts can I compare?

How does the capability recommend a version bump?

Can I detect type narrowing in OpenAPI?

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