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MCP server

Connect Claude, Cursor, or any MCP client to ChangeThisFile — convert files between 999 routes with two tools, no API key.

ChangeThisFile ships a remote Model Context Protocol server. Any MCP-capable client — Claude.ai, Claude Code, Claude Desktop, Cursor, or your own agent — can convert files between 999 conversion routes with no account or API key.


Endpoint	`https://changethisfile.com/mcp`
Transport	Streamable HTTP (POST), MCP spec `2025-03-26`
Authentication	None required
Official registry	`com.changethisfile/mcp`
Source (stdio bridge)	github.com/aadilr/changethisfile-mcp

Connect #

Claude.ai (web): Settings → Connectors → Add custom connector → paste https://changethisfile.com/mcp.

Claude Code:

claude mcp add --transport http changethisfile https://changethisfile.com/mcp

Claude Desktop / Cursor (stdio clients) — add to your MCP config:

{
  "mcpServers": {
    "changethisfile": {
      "command": "npx",
      "args": ["-y", "github:aadilr/changethisfile-mcp"]
    }
  }
}

Anything else — it is plain JSON-RPC 2.0 over HTTPS:

curl -X POST https://changethisfile.com/mcp \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}'

Tools #

convert_file #

Convert a file and get back a temporary download URL. Pass either source_url or base64_content (+ source_format).

Argument	Required	Description
`target_format`	Yes	Target extension, e.g. `pdf`, `mp3`, `json`
`source_url`	One of	Publicly accessible URL of the file (preferred for large files)
`base64_content`	One of	Base64-encoded file content (≤ 25 MB decoded)
`source_format`	With base64	Source extension; auto-detected from URL/filename otherwise
`filename`	No	Filename hint for auto-detection

curl -X POST https://changethisfile.com/mcp \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"convert_file","arguments":{"source_url":"https://example.com/report.docx","target_format":"pdf"}}}'

The result text contains a signed download URL (valid 1 hour); the converted file itself is deleted within 24 hours.

list_conversions #

List every supported route, optionally filtered by source format:

curl -X POST https://changethisfile.com/mcp \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"list_conversions","arguments":{"source_format":"docx"}}}'

Limits #

Limit	Value
`convert_file` calls	5 / minute per IP
Other tool calls	30 / minute per IP
Max input size	25 MB
Download URL validity	1 hour
File retention	Deleted within 24 hours

Need more? Get a free API key (1,000 conversions/month) and use the authenticated REST API, or see pricing for paid tiers.

Use as an Agent Skill #

For skills-capable agents (Claude Code, Codex CLI, Cursor, Gemini CLI, Copilot, and others), install the file-conversion skill — it uses the MCP tools when connected and falls back to a bundled script over plain HTTPS otherwise:

npx skills add aadilr/changethisfile-mcp

Claude Code users can alternatively install the plugin (bundles the MCP server + skill): /plugin marketplace add aadilr/changethisfile-mcp then /plugin install changethisfile@changethisfile.

Troubleshooting #

"Rate limit exceeded (5/min per IP)" — wait 60 seconds, or switch to an API key for higher per-key limits.

"Unsupported conversion: X→Y" — the error lists valid targets for your source format; call list_conversions to browse all routes, or see supported formats.

"File too large" — the no-auth MCP path caps inputs at 25 MB. Use the authenticated API for files up to 5 GB (plan-dependent).

Download URL returns 410/expired — signed URLs last 1 hour. Re-run the conversion to get a fresh URL.

GET /mcp returns 405 — expected. The server is POST-only (no SSE stream); MCP clients fall back to POST mode automatically.

Tools don't appear in your client — remove and re-add the server (Claude.ai: Settings → Connectors; Claude Code: claude mcp remove changethisfile then re-add). Verify the endpoint responds with the curl tools/list example above.

Conversion fails with a 5xx — transient backend issue; retry once, then check system status or email support@changethisfile.com.