Question 1

What is Fixzi?

Accepted Answer

Fixzi monitors MCP server tool schemas, API response contracts, and AI model output schemas for breaking changes, and provides a free suite of developer tools for validating, formatting, comparing, and converting JSON and XML.

Question 2

Is Fixzi only a JSON validator?

Accepted Answer

Fixzi's core products are monitoring tools: MCP Server Monitor (watches MCP tool schemas for drift), API Contract Monitor (detects breaking changes in HTTP API responses), and AI Response Validator (monitors LLM JSON output against a schema). It also includes free JSON and XML tools for validation, formatting, diffing, and conversion.

Question 3

What can developers do with Fixzi?

Accepted Answer

Developers can monitor MCP servers for tool schema drift, monitor API endpoints for contract-breaking changes, monitor AI model outputs for schema drift, validate and fix JSON and XML, compare JSON and XML payloads, and convert between JSON, XML, YAML, TOML, and CSV.

Question 4

Is Fixzi free to use?

Accepted Answer

Yes. Fixzi includes free developer tools for JSON and XML validation, formatting, diff, and conversion. Monitoring features are also available free on every account: 1 MCP monitor, 1 API contract, and 1 AI validator, each checked daily with email alerts included.

Question 5

Can Fixzi help with API response validation?

Accepted Answer

Yes. Fixzi's API Contract Monitor saves your expected API response and checks the live endpoint on a schedule, alerting you when the response structure changes. It also monitors MCP server tool schemas and AI model output for schema drift.

Your MCP servers, APIs, and AI outputs can break — while still returning 200. Catch silent breaking changes before your users do. — Fixzi monitors MCP tool schemas, API contracts, and AI model outputs for breaking changes. Email alerts free on every account.