PSeudo JS
PSeudo JS is a JavaScript emulator for the PlayStation (PSX) that runs on the web and can load some commercial games.
What PSeudo JS is
PSeudo JS is a JavaScript emulator for the PlayStation (PSX) that runs on the web and can load some commercial games. Its code combines .h headers with .js files, inlining modular code before runtime, and supports ES5 JavaScript and later. Building it requires the Clang compiler and a terminal command. To run it, use a localhost server such as Apache; testing also requires a valid BIOS file in the bios folder. The maker does not provide guidance on finding a BIOS file.
The project uses WebAudio and WebGL. Its repository lists progress for CPU Mips R3000A at 95%, DMA at 90%, CD Decoder at 75%, Audio at 60%, and XA Audio at 10%. The maker describes speed and the overall experience as mediocre at best, and timing as quite inaccurate. The CPU uses a slow interpreter; a JavaScript tracer to improve speed is planned for later. PSeudo JS is free and open source under the Apache 2.0 license.
Good
- Runs in a web browser.
- Can load some commercial games.
- Compatible with ES5 JavaScript and later.
- Free and open source under Apache 2.0.
Watch out
- Requires a localhost server to run.
- Testing requires a valid BIOS file.
- Speed and overall experience are described as mediocre.
- Timing is quite inaccurate.
Who it suits
PSeudo JS may suit developers or technically inclined users looking for a web-based PSX emulator who can build and run software locally. It is less suited to anyone expecting accurate timing or strong performance.
Verdict
PSeudo JS offers a free, open-source way to run a PSX emulator on the web, but setup requires a local server and BIOS file. Its stated performance and timing limitations are important considerations.
The facts
Each one read from PSeudo JS's own pages, with the date it was checked.
Where it runs
- BIOS sourcing
- The maker says they will not provide information on where to find a BIOS file.checked 9 Oct 2026
- Browser technologies
- The project repository tags it with WebAudio and WebGL.checked 4 Oct 2026
What it does
- Build requirement
- Building PSeudo JS uses the Clang compiler and the project’s build command in a terminal.checked 9 Oct 2026
- Codebase
- It uses .h headers alongside .js files, inlines modular code for optimization before runtime, and is compatible with ES5 JavaScript onwards.checked 4 Oct 2026
- Code structure
- The project uses .h headers alongside .js files, inlining modular code for optimization before runtime on the VM.checked 9 Oct 2026
- CPU implementation
- The project uses a slow CPU interpreter, with an attempt to speed it up using a JavaScript tracer planned later.checked 4 Oct 2026
- Game support
- The emulator can load some commercial games.checked 9 Oct 2026
- JavaScript compatibility
- The codebase is compatible with ES5 JavaScript and later.checked 9 Oct 2026
- License
- PSeudo JS is open source under the Apache 2.0 license.checked 9 Oct 2026
- Live build
- The maker’s site links to a live build at https://naden.co/pseudo.checked 9 Oct 2026
- Performance limit
- The maker describes the speed and overall experience as mediocre at best and says the emulator is quite inaccurate on timing.checked 9 Oct 2026
- Performance limitation
- The maker describes speed and overall experience as mediocre at best and timing as quite inaccurate.checked 4 Oct 2026
- Progress
- The repository lists CPU Mips R3000A at 95%, DMA at 90%, CD Decoder at 75%, Audio at 60%, and XA Audio at 10%.checked 4 Oct 2026
- Purpose
- PSeudo JS is a PlayStation (PSX) emulator written in JavaScript.checked 9 Oct 2026
- Run requirement
- The project must run from a localhost server such as Apache, and testing requires a valid BIOS file in the bios folder.checked 9 Oct 2026
- What it does
- PSeudo JS is a PlayStation (PSX) emulator based on JavaScript.checked 4 Oct 2026
The company
- Maker
- The maker’s site identifies the company as Nadenco Smpc and gives Athens, Greece as its location.checked 9 Oct 2026