# Fixzi

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

Fixzi (https://fixzi.ai) provides monitoring for MCP servers, API contracts, and AI model outputs — alerting on breaking changes before users hit them — plus free and Pro developer tools for JSON and XML workflows. Designed for teams shipping AI agents and MCP servers, developers integrating third-party APIs, and anyone who works with structured data.

## Monitoring Products

- [MCP Server Monitor](https://fixzi.ai/mcp-monitors): Monitor MCP server tool schemas on a schedule. Detects BREAKING (type changes, removed tools/parameters, added required fields), WARNING (renamed tools, description changes, annotation changes), and INFO (added tools/parameters) severity changes. Email alerts free; Slack on Pro; webhooks on Pro+.
- [API Contract Monitor](https://fixzi.ai/api-contract-monitoring): Monitor HTTP API endpoints on a schedule (15 min to daily) and detect breaking response changes. Email, Slack, or webhook alerts classified by severity.
- [AI Response Validators](https://fixzi.ai/ai-response-validators): Monitor LLM JSON output (OpenAI, Anthropic) against a JSON Schema on a schedule. Detect AI output schema drift before it breaks production.

## Free MCP Tools

- [MCP Server Checker](https://fixzi.ai/tools/mcp-server-checker): Free one-off tool — paste an MCP server URL and get an instant health report: connection timing, protocol handshake metadata, full tool list, and quality findings. No account required. Bearer token used once and never stored.

## Free Developer Tools

- [JSON Validator](https://fixzi.ai/json-validator): Validate, fix, format, beautify, minify, and convert JSON online. Free, no account required.
- [XML Validator](https://fixzi.ai/xml-validator): Validate, fix, format, beautify, minify, and convert XML online. Handles attributes, namespaces, and CDATA.
- [JSON Diff](https://fixzi.ai/json-diff): Compare two JSON payloads side by side and detect added, removed, or changed fields. Supports ignore-keys configuration.
- [XML Diff](https://fixzi.ai/xml-diff): Compare two XML documents and detect structural, attribute, and value differences.
- [JSON Schema Generator](https://fixzi.ai/json-schema-generator): Generate JSON Schema (draft-07 or 2020-12) from sample JSON data with required field and type inference.
- [JSON Schema Validator](https://fixzi.ai/json-schema-validator): Validate JSON against a JSON Schema and find missing fields, type errors, and constraint violations.
- [JSON to TypeScript](https://fixzi.ai/json-to-typescript): Convert JSON samples into TypeScript interfaces for frontend and API development.
- [JWT Decoder](https://fixzi.ai/jwt-decoder): Decode JWT tokens and inspect header, payload, claims, expiry, and issuer. Client-side only.

## MCP Integration

Fixzi provides a Model Context Protocol (MCP) server at https://fixzi.ai/api/mcp (Streamable HTTP, JSON-RPC 2.0). Compatible with Claude Code, Cursor, Windsurf, and other MCP-enabled AI editors. Requires a Pro+ plan and an API token with `validators:read` ability.

Supported tools:

AI Validator tools:
- fixzi_list_validators — list all AI output validators in the account
- fixzi_get_validator — get full details of a specific validator
- fixzi_run_check — run a live validation check (requires validators:check ability)
- fixzi_list_checks — browse recent check history for a validator

Monitor tools:
- fixzi_list_monitors — list all monitors (API Contract, AI Validator, MCP) across all types
- fixzi_get_monitor_status — current status, last check result, consecutive failures
- fixzi_get_recent_changes — change log since a given date with severity, change_type, before/after
- fixzi_get_current_snapshot — current tool list for an MCP monitor (names, descriptions, inputSchema)
- fixzi_run_check_now — trigger an immediate check outside the normal schedule (requires monitors:write)
- fixzi_create_mcp_monitor — create an MCP monitor and run a baseline check (requires monitors:write)

## Blog

Developer guides on JSON, XML, API validation, and schema monitoring:

- [How to Monitor Your MCP Server for Breaking Changes](https://fixzi.ai/blog/monitor-mcp-server-breaking-changes) — Pillar post: snapshot tools/list as a contract, three severity tiers with examples, CI snapshot tests vs continuous monitoring, Fixzi setup walkthrough.
- [How to Test an MCP Server: Inspector, CI Snapshots, and Continuous Monitoring](https://fixzi.ai/blog/how-to-test-mcp-server) — Honest three-way comparison with a GitHub Actions CI snippet and a side-by-side feature table.
- [Why HTTP 200 Doesn't Mean Your MCP Server Is Working](https://fixzi.ai/blog/mcp-server-200-but-broken) — The four MCP health layers (transport, protocol, contract, behavioral) with a walkthrough of one deploy breaking contract while all HTTP checks pass.
- [What Is Tool Schema Drift?](https://fixzi.ai/blog/what-is-tool-schema-drift) — Definition-first explainer with full 13-row change-type taxonomy, severity ratings, and four real-world causes of innocent drift.
- [How to Fix Invalid XML](https://fixzi.ai/blog/fix-invalid-xml)
- [How to Validate LLM Output in Production](https://fixzi.ai/blog/validate-llm-output-in-production)
- [API Contract Monitoring vs API Testing](https://fixzi.ai/blog/api-contract-monitoring-vs-api-testing)
- [API Response Schema Drift](https://fixzi.ai/blog/api-response-schema-drift)
- [Top 10 Common JSON Errors and How to Fix Them](https://fixzi.ai/blog/common-json-errors-and-fixes)
- [How to Fix Invalid JSON](https://fixzi.ai/blog/how-to-fix-invalid-json)
- [JSON Diff Tool Guide](https://fixzi.ai/blog/json-diff-tool)

## Pricing

- Free: 1 MCP monitor · 1 API contract · 1 AI validator (each checked daily) · email alerts · 20 AI fixes/month · 2 MB file limit
- Pro: ₹299/month or $9.99/month — 5 monitors of each type, hourly checks, Slack alerts, 250 AI fixes/month
- Pro+: ₹999/month or $24/month — unlimited monitors, 15-minute checks, webhook alerts, CI/CD API access, MCP server access

## Company

- Website: https://fixzi.ai
- About: https://fixzi.ai/about
- Contact: https://fixzi.ai/contact
- Founder: Rohit Mittal