Pdfmonkey is a PDF generation platform: you upload an HTML/CSS template, call their API with JSON data, and receive a rendered PDF. It's designed for invoice generators, certificates, reports, and any workflow where PDFs are produced from dynamic data. ChangeThisFile converts files — a DOCX arrives, a PDF leaves. An MP4 arrives, an MP3 leaves. No templates, no data binding, just format conversion across 690 routes.
These products are often found in adjacent searches but serve fundamentally different needs.
Quick verdict
For generating PDFs from templates + data (invoices, certificates, reports): Pdfmonkey. Template management, variable substitution, and batch generation are its core strengths.
For converting an existing file to a different format: ChangeThisFile. 690 routes, free tier, call /v1/convert with curl or any HTTP client.
For free API access: ChangeThisFile. 1,000 conversions/month with no card. Pdfmonkey has a free tier with limited documents per month.
For zero-dependency integration: ChangeThisFile. No library to install; your existing HTTP client handles everything.
Pricing comparison
| Plan | ChangeThisFile | Pdfmonkey |
|---|---|---|
| Free tier | 1,000 conversions/month (no card) | Small free tier available (limited docs/month — check pdfmonkey.io) |
| Entry paid | $29/mo — 10,000 conversions | Starter plan from ~$14/mo (per their site at time of writing) |
| Mid tier | $99/mo — 50,000 conversions | Growth and business plans available |
| High volume | $499 Scale / $1,999 Growth | Enterprise custom pricing |
| Browser tool | Free, no signup, unlimited | Dashboard for template management |
Pdfmonkey's pricing reflects template storage, concurrent generation, and monthly document quotas. ChangeThisFile's pricing is per conversion — format-agnostic, flat cost per API call regardless of whether it's a PDF, MP3, or ZIP.
Feature comparison
| Feature | ChangeThisFile | Pdfmonkey |
|---|---|---|
| File format conversion | Yes — 690 routes | No — generates from templates, doesn't convert |
| PDF generation from data | No | Yes — core feature |
| Template management | No | Yes — Handlebars/Liquid templates |
| Free API tier | Yes — 1,000/mo, no card | Limited free tier |
| SDK required | No — curl/fetch/requests directly | Ruby, JavaScript, Python clients available |
| Client-side conversions | Yes — 161 browser routes | No |
| Video / audio / ebook / archive | Yes | No |
| Webhooks | HMAC-signed, stdlib verifiable | Yes — document ready notifications |
| Async generation | Yes (for large files) | Yes — PDF generation is async |
Format and route coverage
Pdfmonkey's output is always PDF — it generates PDFs from HTML/CSS templates populated with JSON data. That's a complete use case for invoicing, certificates, and reports, but the tool has no scope for non-PDF conversions.
ChangeThisFile's 690 routes span images (JPG, PNG, WebP, HEIC, SVG, AVIF, GIF, BMP, ICO, TIFF, PSD), documents (PDF, DOCX, ODT, RTF, HTML, Markdown), spreadsheets (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 variants), and fonts (TTF, OTF, WOFF, WOFF2). ChangeThisFile also converts documents to PDF from DOCX, ODT, HTML, and RTF source formats — no template required.
Privacy and data handling
ChangeThisFile client-side routes process images, data files, HTML, Markdown, fonts, and more entirely in the browser. Zero upload for those formats. Architecture-enforced, not policy-based.
ChangeThisFile server-side routes upload over HTTPS, convert, return, and auto-delete. 24-hour R2 retention for async jobs only.
Pdfmonkey stores templates on their platform (they must, as a template management product). Generated PDFs are accessible via URLs after generation, with configurable retention. If your generated PDFs contain sensitive data (personal info, financial records), check their retention and access policies.
Developer experience: no SDK required
Pdfmonkey ships client libraries for Ruby, JavaScript, and Python. Their async generation workflow (create document → wait for webhook → retrieve PDF URL) benefits from a structured SDK.
ChangeThisFile's API doesn't need wrapping. Send a file, name the target, receive the conversion. One synchronous POST. No library to install, no async polling cycle for typical document conversions, no breaking changes to track. We removed our SDKs because they added maintenance surface area without adding value — your HTTP client handles everything.
const form = new FormData();
form.append('file', fs.createReadStream('report.docx'));
form.append('target', 'pdf');
const res = await fetch('https://changethisfile.com/v1/convert', {
method: 'POST',
headers: { Authorization: 'Bearer ctf_sk_your_key' },
body: form
});
fs.writeFileSync('report.pdf', Buffer.from(await res.arrayBuffer()));
Get your free key at changethisfile.com/v1/keys/free.
When to choose which
| Use case | Recommended |
|---|---|
| Generate PDFs from data + templates (invoices, certs) | Pdfmonkey |
| Convert an existing file to a different format | ChangeThisFile |
| Free API tier, no card | ChangeThisFile |
| Zero-dependency API integration | ChangeThisFile |
| DOCX/HTML/ODT → PDF without a template | ChangeThisFile |
| Video, audio, image, ebook conversion | ChangeThisFile |
| Privacy-sensitive file conversion | ChangeThisFile (client-side routes) |
If you're generating PDFs from dynamic data — populating invoice templates with line items, rendering certificates with names — Pdfmonkey's template system is the right approach. If you have an existing file and need it in a different format — DOCX to PDF, HTML to PDF, MP4 to MP3 — ChangeThisFile's free tier handles that with one HTTP call and no library to install. These tools complement rather than compete with each other.