ChangeThisFile vs API2PDF: General Converter vs Multi-Engine PDF API

API2PDF pitches choice: Headless Chrome, LibreOffice, or wkhtmltopdf for your HTML→PDF conversions. If you've worked with these engines directly you know they produce different output, and sometimes the right engine matters for a specific document type.

ChangeThisFile takes a different approach: one endpoint, source auto-detected from filename, no engine selection required. The routing logic picks the right engine for your format. If you want HTML→PDF, it works. If you want DOCX→PDF, MP4→MP3, or HEIC→JPG, same endpoint — no engine selection required, no client library to maintain.

Quick verdict

For HTML→PDF with Headless Chrome rendering: API2PDF is a good option. Chrome-rendered PDFs preserve web fonts, modern CSS, and JavaScript-rendered content better than LibreOffice or wkhtmltopdf.

For document/file conversion beyond PDF: ChangeThisFile. API2PDF is PDF-focused; ChangeThisFile handles images, video, audio, archives, ebooks, and fonts.

For free usage: ChangeThisFile is ahead — 1,000/mo, no card, no watermark. API2PDF has a generous entry tier too ($0 for first 500, then credits).

For developer simplicity: ChangeThisFile. Source auto-detected, one endpoint, call it directly with curl or any HTTP client. API2PDF also works via plain HTTP but has more parameters (engine selection, options per engine).

Pricing comparison

API2PDF's credit model is pay-as-you-go, which is economical at low volume but unpredictable at scale. ChangeThisFile's flat-rate model gives you a hard ceiling — $29/mo for 10,000 conversions, full stop, no overage surprises.

At high volume (500K+ conversions/mo), compare API2PDF's credit bundle pricing against ChangeThisFile's $499/mo Scale plan to find the crossover for your use case.

Feature comparison

Format and route coverage

API2PDF focuses on PDF generation and manipulation. Its three engines cover different HTML→PDF rendering modes, plus LibreOffice for Office document conversion and a PDF utility endpoint for merging. Outside of PDF workflows, API2PDF doesn't operate.

ChangeThisFile covers 690 conversion routes: 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).

For teams that only need PDF generation, API2PDF's engine choice is a genuine feature. For teams with broader conversion needs, ChangeThisFile eliminates the need to integrate multiple APIs.

Privacy and data handling

ChangeThisFile client-side routes (161 routes — images, CSV, JSON, YAML, DOCX→HTML, fonts, and more): files process in your browser. No upload, no server, no data leaves your device. This is architectural, not just policy.

ChangeThisFile server-side routes (document/video/audio/archive conversion): files upload over HTTPS, convert, and are auto-deleted immediately. No retention.

API2PDF is cloud-only. All documents — including your HTML content and any uploaded Office files — traverse their servers. Their documentation notes that files are not stored permanently, but the processing infrastructure handles your content.

Developer experience

ChangeThisFile has no SDK — one POST to /v1/convert, attach your file, specify a target format. Source format is auto-detected from the filename. No engine to choose, no library to install.

curl -X POST https://changethisfile.com/v1/convert \
  -H "Authorization: Bearer ctf_sk_your_key" \
  -F "file=@report.html" \
  -F "target=pdf" \
  --output result.pdf

API2PDF works via plain HTTP too. You POST a JSON body specifying the engine, URL or inline HTML, and options. No SDK required, though client libraries exist for convenience. The extra parameter (engine selection) is the main difference — useful if you know you need Chrome rendering specifically, but overhead if you just want a PDF.

Both APIs are straightforward to call with any HTTP client. ChangeThisFile's file upload model (multipart) differs from API2PDF's JSON body model (URL or base64). For converting existing files, multipart is more natural; for rendering HTML you're generating server-side, JSON body is slightly cleaner.

When to choose which

If you specifically need Headless Chrome rendering for HTML→PDF, API2PDF gives you that choice with a clean API. PDF merging and S3 output are also genuine features ChangeThisFile doesn't offer.

If your use case extends beyond PDF — or if you just want to convert files without thinking about which engine to select — ChangeThisFile's free tier starts at 1,000 conversions/month with no card. Same endpoint handles your DOCX-to-PDF, your HEIC-to-JPG, and your MP4-to-MP3.