ChangeThisFile vs OnlineConvertFree: Which Should You Choose?

OnlineConvertFree covers a lot of formats and has no signup wall for casual use. It's one of the older web converter properties. The tradeoff is a heavy ad load, file size limits on free conversions, and no API access.

ChangeThisFile takes a different approach: fewer ads, client-side processing for common formats, and a developer API that starts free. This comparison walks through where each tool wins.

Quick verdict

For everyday web conversions: ChangeThisFile — same free access, no ads, cleaner experience.

For privacy-sensitive files: ChangeThisFile — images, data files, and fonts convert in your browser without uploading.

For developers: ChangeThisFile only. OnlineConvertFree has no API.

For exotic or niche formats: OnlineConvertFree may cover some formats ChangeThisFile doesn't, particularly legacy document and CAD-adjacent formats. Check both before concluding a format is unsupported.

Pricing comparison

OnlineConvertFree's business model is advertising — the free web tool is funded by display ads. ChangeThisFile is ad-free and monetizes via the API for developers who need programmatic access.

Feature comparison

Privacy and data handling

OnlineConvertFree processes all conversions server-side. Every file you upload is sent to their servers. They have a privacy policy covering file deletion, but the file does leave your device for processing.

ChangeThisFile's browser-based routes handle a wide range of common formats entirely in your tab. Images (JPG, PNG, WebP, GIF, BMP, ICO, AVIF, SVG, TIFF, HEIC, PSD), data formats (CSV, JSON, YAML, TOML, XML, TSV), spreadsheets (XLSX), documents (DOCX→HTML, HTML↔Markdown), image-to-PDF, and all font formats: none of these upload anything. The conversion runs in JavaScript in your browser.

For server-side routes (video, audio, complex documents, archives), ChangeThisFile uploads over HTTPS and auto-deletes after conversion — same as any responsible web converter.

API and developer experience

OnlineConvertFree has no API. Automating conversions via their web tool would require scraping, which is brittle and against their terms.

ChangeThisFile's API has no SDK — the endpoint is the SDK. A single POST with your file and target format:

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

Source format is detected automatically from the filename extension. Get a free key at changethisfile.com/v1/keys/free — 1,000 calls/month, no card required. Paid tiers start at $29/mo for 10,000 conversions.

Format coverage

OnlineConvertFree has a broad catalog accumulated over many years, covering document, image, audio, video, ebook, and some CAD-adjacent formats. It's one of the more comprehensive web converter catalogs for obscure or older formats.

ChangeThisFile focuses on 690 routes across the formats most developers and users actually need: all major image formats, documents (PDF, DOCX, ODT, RTF), spreadsheets, video (MP4, MKV, WebM, AVI, MOV), audio (MP3, WAV, FLAC, AAC), ebooks (EPUB, MOBI, AZW3, FB2, CBR/CBZ), archives (ZIP, RAR, 7Z, TAR and all .tar.* variants), and fonts.

For highly niche or legacy formats, OnlineConvertFree may have broader coverage. For mainstream developer and user needs, ChangeThisFile's coverage is comprehensive.

When to choose which

If you're using OnlineConvertFree for casual conversions and the ads don't bother you, it's a functional tool. But for privacy, developer access, or an ad-free experience, ChangeThisFile is better in every relevant dimension. Try the API free — 1,000 conversions/month, no card.