Format Factory has been a staple Windows utility since 2008 — a free, all-in-one desktop tool for converting video, audio, images, and documents. It's widely used by non-technical users who want a simple GUI and don't want to pay for anything.
ChangeThisFile is built for a different use case: HTTP access to conversion from code. Same file types, different interface. This comparison is direct about when Format Factory wins (free local conversions on Windows) and when ChangeThisFile wins (API access, automation, cross-platform backends).
Quick verdict
For Windows users converting files manually: Format Factory. It's free, has a GUI, and doesn't require internet access or an account.
For developers integrating file conversion into an app: ChangeThisFile. One HTTP POST, file + target format, source auto-detected — no desktop app to wrap, no Windows dependency.
For macOS/Linux users: Format Factory is Windows-only. ChangeThisFile works from any platform via HTTP.
For multi-user or SaaS products: ChangeThisFile. Format Factory has no API or multi-tenant design.
Pricing comparison
| Plan | ChangeThisFile | Format Factory |
|---|---|---|
| Free tier | 1,000 conversions/month (no card) | Fully free, unlimited |
| Entry paid | $29/mo — 10,000 conversions | Free |
| High volume | $499 Scale / $1,999 Growth | Free (local compute) |
| Platform | Any (HTTP) | Windows only |
| Internet required | Yes (API calls) | No |
Format Factory is free for personal desktop use. ChangeThisFile's pricing reflects hosted compute — you're paying for video/audio/document conversion running on managed servers you don't have to maintain.
Feature comparison
| Feature | ChangeThisFile | Format Factory |
|---|---|---|
| HTTP API | Yes — POST /v1/convert | No |
| GUI | Web browser | Yes — Windows desktop |
| Platform | Any (HTTP) | Windows only |
| Video conversion | Yes — FFmpeg | Yes |
| Audio conversion | Yes — FFmpeg | Yes |
| Image conversion | Yes — 161 client-side routes | Yes |
| Document conversion | Yes — LibreOffice + Pandoc | Limited |
| Ebook conversion | Yes — Calibre | No |
| Archive conversion | Yes — 7-Zip | No |
| Batch processing | Multiple API calls / scripting | Yes — GUI queue |
| Internet required | Yes | No |
Developer experience
ChangeThisFile API — the endpoint is the SDK. No installation, no language bindings, no wrapper libraries. One POST with file and target. Source format is auto-detected from the filename.
curl -X POST https://changethisfile.com/v1/convert \
-H "Authorization: Bearer ctf_sk_your_key" \
-F "file=@video.avi" \
-F "target=mp4" \
--output converted.mp4
Same call from Python, Node, Go, PHP — any language that can make an HTTP request. Free API key at changethisfile.com/v1/keys/free (no card).
Format Factory has no programmatic API. Automation requires launching the GUI application or using AutoHotkey/Windows scripting to drive the UI — fragile and not suitable for server-side use.
When to choose which
| Use case | Recommended |
|---|---|
| Manual Windows desktop conversions | Format Factory (free, no internet) |
| Non-technical Windows users | Format Factory |
| API access from a backend | ChangeThisFile |
| macOS or Linux users | ChangeThisFile (Format Factory is Windows-only) |
| Automated conversion pipeline | ChangeThisFile |
| SaaS or web app feature | ChangeThisFile |
| Ebook or archive conversion | ChangeThisFile (Format Factory doesn't cover these) |
Honest take
Format Factory is a solid free Windows tool for users who want a GUI and offline conversions. If you're on Windows and converting files manually, it covers most needs at zero cost.
ChangeThisFile wins on platform reach (any OS, any language, any backend) and API design. It also covers more file types — ebook conversion via Calibre, archive conversion via 7-Zip, and document conversion via LibreOffice and Pandoc go beyond what Format Factory handles. The 1,000 free conversions/month is enough for most developers testing an integration or running a small app.
Format Factory is a great free Windows app. If you're on Windows converting files by hand, it does the job. If you need file conversion in code — from a web backend, a script, or a product feature — ChangeThisFile's free API tier gets you started in minutes without installing anything.