MustardOS review
A capable free frontend for supported Anbernic and TrimUI handhelds.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
MustardOS, also called muOS, is open-source custom firmware with a configurable, themeable frontend for selected retro handhelds. It is aimed at owners of supported Anbernic and TrimUI devices who want game browsing, emulator launching, controller navigation, and device controls in one portable interface. The supported hardware includes specified RG28XX, RG34XX, RG35XX, RG40XX, RGCUBEXX, TrimUI Brick, and TrimUI Smart Pro models.
Its main strength is breadth within the handheld frontend category. MustardOS can browse game content across SD1, SD2, and USB storage, organize collections, show recently played history, and launch bundled emulator cores and applications including RetroArch, PPSSPP, and ScummVM. PortMaster support adds compatible ports, while device configuration covers connectivity, power, storage, overlays, and interface behavior. Controller hotkeys support navigation, save states, screenshots, and system actions, and backup and restore archives help manage device data.
Installation centers on SD-card images for supported hardware, followed by updates distributed for those devices. That approach suits owners comfortable managing handheld firmware and storage, but the product's value depends on matching the supported model list before installation. MustardOS is a strong pick for users who want a free, open-source frontend with bundled emulators, storage browsing, collections, backups, and device configuration. It is less suitable for owners of unsupported handhelds or anyone who specifically needs built-in scraping. Users seeking a narrow, model-agnostic frontend should consider an alternative with broader hardware coverage.
MustardOS pros and cons
- Where it wins
- Bundled RetroArch, PPSSPP, ScummVM, and emulator cores
- Browses SD1, SD2, and USB storage with collections and history
- Includes PortMaster, backups, hotkeys, themes, and device settings
- Where it doesn't
- Support is limited to specified Anbernic and TrimUI models
- Does not include game-content scraping
- Requires SD-card image installation and updates
MustardOS fact sheet, pricing and score →
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