c64js review
A free browser emulator for quick PRG demos, with partial graphics support.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
c64js is a free, open-source Commodore 64 emulator delivered as a browser demo. It is aimed at people who want to inspect or demonstrate compatible .prg-format ROM files directly on the web, without installing a desktop emulator. The interface uses a canvas, and files can be loaded by dropping them onto that canvas. Its implementation is written from scratch in vanilla JavaScript, making it a focused fit for browser-based PRG demonstrations rather than a full replacement for a complete Commodore 64 environment.
The web-first design keeps the interaction straightforward: open the browser interface, then drop a supported .prg file onto the emulator canvas. The published project also includes npm and Gulp instructions for building a production distribution, which gives developers a defined path for working with the source. Its platform scope is narrow, however, with web listed as the supported platform and .prg as the supported disk or tape format.
The main technical boundary is emulation depth. c64js includes partial VIC-II graphics emulation, but the VIC-II implementation is incomplete, SID sound is not emulated, and only a limited number of ROMs are expected to work correctly. That makes it suitable for quick visual demos and lightweight experimentation with compatible PRG files. Users who need broader software compatibility, complete graphics behavior, sound emulation, or wider media-format support should choose a more complete Commodore 64 emulator instead.
c64js pros and cons
- Where it wins
- Runs in a web browser with a canvas-based interface
- Loads .prg files by dropping them onto the emulator canvas
- Open-source project built with vanilla JavaScript and MIT licensing
- Where it doesn't
- VIC-II graphics emulation is incomplete
- SID sound is not emulated
- Only a limited number of ROMs work correctly
c64js fact sheet, pricing and score →
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