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Introduction

The conversion API for AI builders. 690+ formats, one HTTP call.

The ChangeThisFile API is a single, predictable HTTP surface for converting files between 690+ formats — images, video, audio, documents, spreadsheets, ebooks, archives, and fonts.

It's built for AI builders, automation pipelines, and back-office workflows that need flat, predictable pricing and broad format coverage.

Hello world

curl -X POST https://changethisfile.com/v1/convert \
     -H "Authorization: Bearer ctf_sk_...your_key_here..." \
     -F "file=@photo.png" \
     -F "target=jpg" \
     --output photo.jpg

That's it — file in, file out. The source format is auto-detected from the filename, so target is the only field most callers ever need. No SDK required — any HTTP client works.

Why ChangeThisFile #

690+ conversion routes

Every common format pair (PNG↔JPG, DOCX→PDF, MOV→MP4, EPUB↔MOBI, RAR→ZIP, …) plus long-tail edges like AI/EPS, RAW photos, and font formats.

Sync or async

POST /v1/convert returns the converted file inline. POST /v1/jobs queues async work — perfect for big files and queue workers.

Idempotent + signed webhooks

Stripe-style Idempotency-Key, HMAC-signed webhooks with replay protection, predictable error envelope.

Free tier, no card

1,000 conversions/month, 25 MB file cap, 10 req/min. Get a key →

What you can build #

AI document pipelines — convert user uploads (DOCX, PDF, HEIC, …) into model-friendly formats before ingesting.
Image transformation services — resize, transcode, or normalise format inside your own product.
Compliance / archival flows — emit PDF/A from Office docs, batch-convert legacy media for storage.
Internal tools — anywhere your team is currently shelling out to FFmpeg, LibreOffice, or ImageMagick by hand.

How the docs are organised #

Quickstart — get a free key and run your first conversion in under five minutes.
Conversions — sync vs async, file-size limits, quality presets.
Webhooks, Idempotency, Rate limits, Errors — the must-read concepts (with copy-pasteable Python and JavaScript snippets).
Formats — every supported route, auto-generated from the live engine.
API reference — every endpoint, generated from the OpenAPI 3.1 spec.

Need help? #

Email support@changethisfile.com or file an issue at github.com/aadilr/changethisfile.