File Conversion Skill for Claude
Convert files between formats — PDF to Word, HEIC to JPG, MP4 to MP3, CSV to JSON, EPUB to MOBI, and 999 total routes across images, video, audio, documents, data, fonts, ebooks, and archives. Free via changethisfile.com, no API key or signup. Use when the user needs a file converted to a different format.
Install
one command, takes just this skill from the repositorynpx skills add https://github.com/wshobson/agents --skill file-conversionThe instruction itself
5 sections, as written by the authorFile Conversion (ChangeThisFile)
Convert files between 999 conversion routes using the free ChangeThisFile service. No account or API key required. Conversions run server-side (FFmpeg, LibreOffice, Calibre, 7-Zip, sharp, Ghostscript); files are deleted within 24 hours.
Decision order
- If ChangeThisFile MCP tools are available (
changethisfile:convert_file,changethisfile:list_conversions) — use them directly.convert_filetakessource_urlORbase64_content+source_format, plustarget_format, and returns a temporary download URL. - Otherwise, use the bundled script (requires network access to changethisfile.com):
scripts/convert.sh <input-file> <target-format> [output-file]
# e.g. scripts/convert.sh report.docx pdf
# prints the output file path on success
The script path is relative to this skill's directory. It base64-encodes the file, calls the hosted MCP endpoint over plain HTTPS, downloads the result, and writes it next to the input (or to [output-file]).
- Remote file (you have a URL, not a local file) — skip the download/re-upload; one curl does it:
curl -sS -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":"<FILE_URL>","target_format":"pdf"}}}'
The response text contains a download URL — fetch it with curl -o <output>.
Discovering supported routes
Ask before guessing if a conversion is exotic:
curl -sS -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"}}}'
Omit source_format for a grouped summary of all 999 routes.
Limits and errors
- Max input: 25 MB (free path). Larger files: get a free API key (1,000 conversions/month) at https://changethisfile.com/docs/authentication and use
POST /v1/convert. - Rate limit: 5 conversions/minute per IP. On "Rate limit exceeded", wait 60 seconds and retry once.
- "Unsupported conversion: X→Y" errors list the valid targets for that source format.
- Download URLs expire after 1 hour — download immediately, then work with the local file.
Environment notes
- Needs outbound HTTPS to
changethisfile.com. On claude.ai, the code-execution sandbox restricts egress by default — prefer the MCP connector there, or the user can allow the domain under Settings → Capabilities. - Full docs: https://changethisfile.com/docs/mcp
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How to use it
Take wshobson/file-conversion from the repository into ~/.claude/skills for personal
use, or into .claude/skills inside a project.
The agent identifies a skill by the name field in its header. Two skills with the
same name cannot sit side by side — one of them will be ignored.