Prince XML has been the definitive tool for publication-quality HTML-to-PDF since 2002. Publishing houses, government agencies, and technical documentation teams use it because it handles the hard parts: proper hyphenation across languages, OpenType ligatures and kerning, complex multi-column layouts, table headers that repeat across pages, footnotes, cross-references, and the full CSS Paged Media specification.
ChangeThisFile converts files between formats. DOCX to PDF, HEIC to JPG, MP4 to MP3 — 690 routes via one endpoint. Source auto-detected from the filename. For general file conversion with a free tier, it's a simpler starting point. For print-quality typesetting, Prince is in a different category entirely.
Quick verdict
For publication-quality PDF typesetting from HTML: Prince XML. No comparable alternative exists for complex print layouts, technical books, or styled reports. The output quality difference vs. LibreOffice or headless Chrome is significant.
For general file conversion (DOCX→PDF, image formats, video, audio, archives): ChangeThisFile. Broader scope, free tier, one HTTP endpoint.
For budget-conscious teams: ChangeThisFile starts free; Prince XML commercial licenses start at several hundred dollars per server per year.
For self-hosting: Prince can be run on your own servers (it's a CLI tool). ChangeThisFile is cloud-only.
Pricing comparison
| Plan | ChangeThisFile | Prince XML |
|---|---|---|
| Free tier | 1,000 conversions/month (no card) | Free for non-commercial use (watermarked) |
| Entry commercial | $29/mo — 10,000 conversions | ~$500+ per server license (annual) |
| Mid tier | $99/mo — 50,000 conversions | Server license (scales by server count) |
| High volume | $499/mo — 500,000 / $1,999/mo — 5M | Contact for volume licensing |
| Deployment model | Managed cloud API | Self-hosted CLI / library |
Prince's pricing is per-server, not per-conversion. A single server license runs your PDF generation at unlimited volume — the cost model is fundamentally different from per-conversion APIs. At high PDF volume, Prince's upfront cost can be much more economical than per-conversion pricing. At low volume, ChangeThisFile's free tier is obviously cheaper.
DocRaptor is effectively "Prince as a managed API" — if you want Prince quality without running servers, DocRaptor is worth comparing too.
Feature comparison
| Feature | ChangeThisFile | Prince XML |
|---|---|---|
| Free managed tier | Yes — 1,000/mo, no card | No — self-hosted with watermark for non-commercial |
| SDK / CLI required | No — one HTTP POST | Yes — CLI or language bindings (prince command) |
| HTML→PDF quality | Adequate (LibreOffice engine) | Publication-quality (best available) |
| CSS Paged Media | No | Full spec support |
| Hyphenation (multi-language) | Basic | Excellent — built-in dictionaries |
| OpenType features (ligatures, kerning) | No | Yes |
| Complex column layouts, footnotes | No | Yes |
| Self-hosted | No | Yes — runs on Linux/macOS/Windows |
| Image/video/audio/archive conversion | Yes | No |
Format and route coverage
Prince XML takes HTML/CSS/SVG/MathML input and outputs PDF. That's its scope — and within that scope it is exceptional. It handles complex technical documents, styled academic papers, books with complex layouts, and government reports with precision that no browser-based renderer matches.
ChangeThisFile covers 690 routes across image (JPG, PNG, WebP, HEIC, AVIF, SVG, BMP, ICO, GIF, TIFF), document (PDF, DOCX, ODT, RTF, HTML, TXT), spreadsheet (XLSX, CSV, JSON, TSV), video (MP4, MKV, WebM, AVI, MOV, GIF), audio (MP3, WAV, FLAC, AAC, M4A), ebooks (EPUB, MOBI, AZW3), archives (ZIP, RAR, 7Z, TAR), and fonts (TTF, OTF, WOFF, WOFF2).
The overlap is: HTML→PDF. Prince does it far better. ChangeThisFile covers everything else Prince doesn't touch.
Privacy and data handling
Prince XML (self-hosted): runs on your servers or developer machines. HTML content and output PDFs never leave your infrastructure. For sensitive documents — legal, medical, financial — self-hosted Prince means complete data sovereignty.
ChangeThisFile client-side routes (161 routes — images, CSV, JSON, YAML, DOCX→HTML, fonts, and more): files process entirely in your browser. Zero upload, zero server involvement.
ChangeThisFile server-side routes (document/video/audio/archive conversion): files upload over HTTPS, convert, auto-delete. No retention.
For HTML→PDF with sensitive content, self-hosted Prince provides stronger data guarantees than any cloud API including ChangeThisFile's server-side routes.
Developer experience
ChangeThisFile has no SDK — the endpoint is the SDK. POST a file, specify a target format, source auto-detected from filename. Any HTTP client works. No install, no package manager, no version pinning.
curl -X POST https://changethisfile.com/v1/convert \
-H "Authorization: Bearer ctf_sk_your_key" \
-F "file=@document.docx" \
-F "target=pdf" \
--output result.pdf
Prince XML is a command-line tool and C library. Typical integration is via shell: prince input.html -o output.pdf, or via language bindings for Python, PHP, Java, .NET, and others. It's well-documented but requires installation (and a license on your server).
Prince's integration pattern is fundamentally different: you run it on your server, it processes files locally. No HTTP call, no API key, no rate limit. For high-volume local processing, that's an advantage. For a web API integration with no server to maintain, ChangeThisFile is simpler.
When to choose which
| Use case | Recommended |
|---|---|
| Publication-quality HTML→PDF (books, styled reports) | Prince XML |
| Complex CSS Paged Media (footnotes, running headers) | Prince XML |
| Multi-language hyphenation and OpenType typography | Prince XML |
| Self-hosted PDF generation with data sovereignty | Prince XML |
| High-volume local PDF processing (unlimited, no per-conversion cost) | Prince XML |
| General DOCX/ODT/RTF→PDF conversion | ChangeThisFile |
| Image, video, audio, archive, ebook conversion | ChangeThisFile |
| Free managed API, no server, curl-direct | ChangeThisFile |
| Low-volume conversion without a server license | ChangeThisFile |
Prince XML is the honest answer for anyone who needs publication-quality PDFs. If your use case involves book layouts, complex typography, multi-language documents, or print-perfect reports — there's no better tool, and ChangeThisFile isn't a substitute.
For everything else — converting documents, images, video, audio, archives, or ebooks without installing anything or maintaining a server — ChangeThisFile's free tier handles 1,000 conversions/month across 690 routes. One endpoint, call it with curl or any HTTP client.