Cathar

Overview

Cathar covers a substantial span of audio cleanup, from hum and wind reduction to spectral repair, then adds voice-focused enhancement and loudness control. It accepts WAV, MP3, FLAC, OGG, and M4A files, along with audio tracks in MP4 and MKV, and writes WAV, FLAC, or AIFF based on the output filename extension. Batch processing is supported, which makes it more useful for repeatable collections of recordings than a tool limited to one-off edits.

The toolkit is written in pure Rust and avoids ffmpeg, C or C++ code, and system libraries. Its processing stages are tunable DSP rather than opaque neural models, a meaningful advantage for users who need to inspect and adjust how a workflow treats audio. That focus also signals the tradeoff: Cathar is a toolkit to incorporate into a workflow, not a finished desktop editing suite.

Key features

Repair and enhancement

Restoration functions include denoise, de-hum, de-wind, de-click, de-clip, de-reverb, spectral repair, de-plosive, and de-rustle. De-essing, breath removal, voice isolation, and bandwidth extension extend its reach to speech cleanup and enhancement. This range is useful when a pipeline must address several kinds of recording flaws; users looking for a narrowly focused noise reducer may not need so many stages.

For delivery, Cathar offers LUFS loudness normalization and peak normalization. Having both makes the toolkit relevant to workflows with different level targets, rather than limiting it to repair alone.

Integration and optional tools

Effects are plain functions over audio sample slices. Rust projects can call them in-process through the cathar crate, while other pipeline steps can invoke the cathar command-line tool as a stage. The CLI can be installed with cargo install cathar-cli from crates.io. This is a practical fit for code-driven processing, but less direct for users who expect to make edits through a graphical interface.

An optional ml feature adds a GRU-based denoiser that loads open safetensors weights; its inference is deterministic and implemented in Rust. The optional tui features add a terminal audio player and interactive spectrogram viewer. Linux playback requires ALSA headers, a dependency to account for when building that optional feature.

The project includes an illustrated book, Cleaning Up Sound, that explains its concepts and compares Cathar with other audio tools. It is licensed under either Apache License 2.0 or MIT. The latest GitHub release is v0.8.0, and Cathar is in the 0.8.x series before 1.0, so buyers seeking a mature, stable product should weigh that status carefully.

Pricing

Cathar is free, with no paid plan or free trial. The free offering includes the toolkit; the ML denoiser and terminal player and spectrogram viewer are optional features rather than separate paid plans. There are no seat counts or usage quotas to weigh. Its permissive dual licensing is a further advantage for teams deciding whether to use it in their software workflows.

Platforms

Cathar supports Linux and macOS. Its standalone workflow can run from the command line or be embedded in Rust projects through the crate. The optional terminal player has an additional Linux build requirement: ALSA headers.

Who it's for

Cathar is best for Rust developers, audio teams, and technically minded users who want repeatable cleanup and leveling stages they can tune, combine, and integrate into a pipeline. Batch processing and support for common audio and video-container inputs make it a strong fit for processing collections of recordings. It is a weaker match for users who want a conventional editing application, or for teams that need a post-1.0 release.

Pros and cons

• Pro: Broad restoration, voice enhancement, and loudness tools make one toolkit useful across several stages of an audio workflow.
• Pro: Inspectable, tunable DSP and Rust-native integration give developers control over processing and pipeline design.
• Pro: Free access, batch processing, and support for audio tracks inside MP4 and MKV reduce friction for repeat jobs and mixed media inputs.
• Con: Cathar is still before 1.0, which may make it a poor fit for workflows that require a mature release.
• Con: It is a toolkit rather than a finished desktop editor, so users who prefer a graphical editing workflow should look elsewhere.
• Con: Linux playback in the optional terminal tools requires ALSA headers.

Alternatives

Browse Audio Restoration Software for more restoration choices, or AI Audio Restoration Software for tools focused on AI-assisted repair.

• CEDAR Cambridge suits buyers considering a paid, configurable modular hardware and software system on macOS or Windows; its options vary and require contacting CEDAR Audio.
• Neiro is another free option, with Linux, macOS, self-hosted, web, and Windows availability.
• Wave Arts Master Restoration Suite 6 is a paid macOS and Windows option with five restoration plug-ins for $99.00 USD per once; it requires a host that supports audio plug-ins.
• Diamond Cut Audio Restoration Tools 11.09 is a paid Windows alternative for $59.00 USD per once, with one year of free support and a Windows 10-or-later requirement.
• SpectraLayers Pro is a paid macOS and Windows alternative for spectral audio editing, repair, and restoration with AI-assisted processing.
• @audio/denoise is a free web option for readers seeking a web-based alternative.
• Acoustica is a paid macOS and Windows alternative with Standard and Premium plans for different channel counts.
• iZotope RX is a paid macOS and Windows alternative with Elements and Standard plans offering different sets of repair tools.

Verdict

Choose Cathar if you want free, tunable audio restoration that can be embedded in Rust software or run as a pipeline stage. Its breadth and inspectable DSP make it particularly compelling for technical users building repeatable workflows. Look elsewhere if you need a conventional desktop editor or a mature post-1.0 release.