ChangeThisFile vs Zamzar: Which File Converter Wins?

Zamzar launched in 2006 and was one of the first mainstream online file converters. Its email-delivery model was practical in the dial-up era when large files couldn't easily download mid-conversion. Today that model is mostly a friction point — most people want their converted file immediately.

ChangeThisFile was built for how conversions work today: instant results, no email required, with a client-side architecture that keeps sensitive files on your device.

Quick verdict

For speed: ChangeThisFile. Results are immediate — download starts as soon as conversion finishes. Zamzar's free tier has deliberate delays and email delivery.

For format breadth: Zamzar. Their 1,200+ format claim includes many legacy and specialized formats not covered elsewhere.

For privacy: ChangeThisFile. Client-side routes mean common image, data, and font conversions never leave your device. Zamzar is server-side only.

For API access: ChangeThisFile. Free tier with 1,000/mo, no card. Zamzar offers an API on paid plans.

Pricing comparison

Zamzar's deliberate delay on the free tier is a monetization strategy — upgrade to get faster results. ChangeThisFile doesn't throttle conversion speed based on plan.

Feature comparison

Format coverage

Zamzar's 1,200+ format claim is their headline differentiator. This includes formats like old WordPerfect documents, rare CAD formats, obsolete image types from the 1990s, and specialized audio/video formats from broadcast workflows. If you're working with legacy files from old software, Zamzar has genuine breadth that's hard to match.

ChangeThisFile focuses on the 82 formats that cover the vast majority of real-world conversion needs today: image, document, spreadsheet, video, audio, ebook, archive, data, and font formats. 690 routes with explicit, documented support means you know exactly what works.

For common modern formats, both tools have solid coverage. For obscure legacy formats (WordPerfect, old database exports, vintage image formats), Zamzar is the better choice.

Privacy and data handling

Zamzar's entire architecture is server-side. Every file you convert is uploaded to their servers, queued, processed, and either emailed to you or held for download. Files are eventually deleted per their policy.

ChangeThisFile processes 161 routes entirely in your browser. No server, no upload, no transmission. This includes all major image formats (JPG, PNG, WebP, HEIC, GIF, BMP, AVIF, SVG, ICO, TIFF), CSV, JSON, YAML, TSV, XML, TOML, HTML, Markdown, DOCX→HTML, PSD, fonts (TTF/OTF/WOFF/WOFF2), and more.

For business documents, financial spreadsheets, or personal photos, this is a meaningful architectural difference. With client-side conversion, there's no policy to trust — the data simply never leaves your machine.

API and developer experience

Zamzar has an API, but it's available on paid plans only and uses a similar asynchronous model to their web tool: submit a job, get notified when it's done.

ChangeThisFile's API is free to start, synchronous, and requires no account beyond generating a key:

# Get a free key (no card) at changethisfile.com/v1/keys/free
curl -X POST https://changethisfile.com/v1/convert \
  -H "Authorization: Bearer ctf_sk_your_key" \
  -F "file=@document.doc" \
  -F "source=doc" \
  -F "target=pdf" \
  --output document.pdf

Response comes back as the file directly. No webhook, no polling, no job ID to track. For most workflows, this is simpler and lower-latency.

When to choose which

Zamzar is a reliable tool with an impressive legacy format catalog. If you're dealing with files from old software that no other converter handles, Zamzar is worth trying. For modern workflows — instant results, privacy-first image and document conversion, or building an integration — ChangeThisFile is the faster, simpler, and free-to-start option.