The Best Local File Converters in 2026
Not every file conversion needs to involve uploading your files to a stranger's server. Here are the best tools that process everything on your machine.
Why local matters
Cloud converters are convenient, but they come with trade-offs: your files leave your machine, you need an internet connection, upload/download times add latency, and you're trusting a third party with your data. For personal photos, financial documents, client work, or anything sensitive, local conversion is the smarter choice.
What to look for
A good local converter should handle multiple format categories (not just images), work fast, support batch processing, and ideally have both a GUI and CLI for different workflows. Bonus points for preset systems, quality control, and developer-friendly features.
The contenders
ConvX
A Rust-powered universal converter covering 46 formats across images, video, audio, documents, data files, and eBooks. Three surfaces: desktop app, CLI, and MCP server for AI agents. Standout features include size-constrained conversions (set a target file size and ConvX iteratively adjusts quality), 14 built-in presets for platforms like Discord and Instagram, watch mode for auto-converting files, and a unified quality slider that maps intelligently per codec. $20 lifetime.
FFmpeg (CLI)
The gold standard for video and audio processing. Incredibly powerful but with a notoriously steep learning curve. If you know FFmpeg flags by heart, you can do almost anything. If you don't, you'll spend more time on Stack Overflow than actually converting files. Free and open-source.
HandBrake
A solid open-source video transcoder with a clean GUI. Great for video, but limited to video and audio. No images, documents, or data formats. Free.
ImageMagick (CLI)
The venerable image processing toolkit. Supports a staggering number of image formats but is strictly images-only. The CLI syntax can be cryptic. Free and open-source.
LibreOffice (CLI/GUI)
Can convert between document formats (DOCX, PDF, PPTX, etc.) via its headless mode. Not designed as a converter, so the workflow is clunky, but it works. Free and open-source.
How they compare
| Feature | ConvX | FFmpeg | HandBrake | ImageMagick |
|---|---|---|---|---|
| Images | ✓ 11 formats | Limited | — | ✓ |
| Video | ✓ 10 formats | ✓ | ✓ | — |
| Audio | ✓ 10 formats | ✓ | ✓ | — |
| Documents | ✓ 8 formats | — | — | — |
| Desktop GUI | ✓ | — | ✓ | — |
| CLI | ✓ | ✓ | ✓ | ✓ |
| AI integration | ✓ MCP | — | — | — |
| Presets | ✓ 14 | — | ✓ | — |
| Watch mode | ✓ | — | — | — |
| Price | $20 lifetime | Free | Free | Free |
The verdict
If you work across multiple format types and want a single tool that handles everything, ConvX is the most complete option. If you only need video, HandBrake is excellent and free. If you're a CLI power user who already knows FFmpeg, you probably don't need anything else, but ConvX's presets and quality abstraction layer make common tasks significantly faster.