File Conversion

When to use this skill

Use File Conversion when an AI agent needs a reusable SKILL.md workflow for this job: 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.

When not to use it

Skip File Conversion when the task is outside the coding category, or when a more specific skill in this directory already covers the same workflow with clearer triggers.

How to install

1. Personal install: create ~/.claude/skills/file-conversion/SKILL.md (and any bundled scripts) so Claude Code, Claude Desktop, and compatible agents can load it in every project.
2. Project install: commit the same folder at .claude/skills/file-conversion/ so teammates get the skill with the repo.
3. Restart the agent session after copying files so it re-scans the skills directory, then ask for the task in words that match the skill description.

Full install guide for Claude, Cursor, and Codex

What this skill does

# File 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

1. **If ChangeThisFile MCP tools are available** (`changethisfile:convert_file`, `changethisfile:list_conversions`) — use them directly. `convert_file` takes `source_url` OR `base64_content` + `source_format`, plus `target_format`, and returns a temporary download URL. 2. **Otherwise, use the bundled script** (requires network access to changethisfile.com):

```bash 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]`).

3. **Remote file (you have a URL, not a local file)** — skip the download/re-upload; one curl does it:

```bash 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:

```bash 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

Intended uses

• Use File Conversion when this documented workflow matches the task.