Transmute

Free plan APISelf-hostedWeb

What Transmute is

Transmute is a free, self-hosted converter and compressor for images, video, audio, data, documents, 3D models, and draw.io diagrams. It can compress images, PDFs, audio, video, and GIFs at selectable levels while retaining each file’s format. The maker says files remain on your own hardware rather than going to third-party servers, and provides a Docker Compose quickstart for deployment. Transmute also exposes the conversions available in its interface through a REST API, with documentation at /api/docs when running. Its project README lists user accounts, role-based access, API keys, and OIDC sign-in; named provider options include Authentik and Authelia. The interface offers seven themes and dark and light modes. The GitHub repository identifies the software as MIT licensed. The Free, open source plan costs nothing, with no file-size limits, watermarks, or rate limits and no paid tiers. Cloud conversion is not available. For use beyond a trusted local network, the README recommends a reverse proxy with TLS and rate limiting.

Who it suits

Transmute suits people who want to convert files on their own hardware, including teams that need API access or user and role controls. It is a self-hosted option rather than a cloud conversion service.

What it does well

Supports conversions across seven listed file categories.
Compression offers selectable levels while preserving format.
Conversions are also available through a REST API.
Free plan lists no size or rate limits.
MIT licensed, with seven interface themes.

What to know first

Cloud conversion is not available.
Exposed deployments need a reverse proxy, TLS, and rate limiting.

Plans

Plan	Billed and limits	Price
Free, open source	No file size limits · no watermarks · no rate limits · no paid tiers	Free

As transmute.sh lists them, read 11 Oct 2026. The maker's own page has the final word.

Verdict

Transmute combines broad file conversion and compression with local deployment and REST API access. It is a fit for users who can run and secure the software on their own hardware.

Facts from Transmute's own pages

API: The homepage says every conversion available through the interface is also available through a REST API, with API documentation at /api/docs when running. · transmute.sh, 11 Oct 2026
Audience: The maker describes Transmute as a self-hosted option for people who want private file conversions on their own hardware. · transmute.sh, 11 Oct 2026
Authentication: The project README lists built-in user accounts, role-based access, API keys, and OIDC single sign-on support. · github.com, 11 Oct 2026
Compression: It compresses images, PDFs, audio, video, and GIFs while keeping their format, with selectable compression levels. · transmute.sh, 11 Oct 2026
Conversions: The homepage lists image, video, audio, 3D model, data, document, and draw.io diagram conversions. · transmute.sh, 11 Oct 2026
Deployment: The maker provides a Docker Compose quickstart for running Transmute on the user's hardware. · transmute.sh, 11 Oct 2026
Deployment security: The project README recommends placing Transmute behind a reverse proxy with TLS and rate limiting if exposing it beyond a trusted local network. · github.com, 11 Oct 2026
License: The project's GitHub repository identifies the software as MIT licensed. · github.com, 11 Oct 2026
OIDC integrations: The homepage names Authentik, Authelia, and other OpenID Connect providers as sign-in options. · transmute.sh, 11 Oct 2026
Privacy: The maker says files stay on the user's own hardware and are not uploaded to third-party servers. · transmute.sh, 11 Oct 2026
Purpose: Transmute is a self-hosted file converter and compressor for images, video, audio, data, documents, and 3D models. · transmute.sh, 11 Oct 2026
Themes: The homepage says the interface includes seven themes and supports dark and light modes. · transmute.sh, 11 Oct 2026

Where Transmute stands on Freedom251

File Conversion Software#36 of 69