JSSpeccy 3 is a ZX Spectrum emulator that runs in a web browser. It emulates the Spectrum 48K, Spectrum 128K and Pentagon, including documented and undocumented Z80 instructions. Its display emulation handles scanline and multicolour effects cycle by cycle, with 100%, 200%, 300% and fullscreen display modes. Audio supports AY and beeper output. The emulator loads SZX, Z80 and SNA snapshots, along with TZX and TAP tape images using traps. Supported files can also be opened from ZIP archives. JSSpeccy 3 runs in a Web Worker, and its core is compiled to WebAssembly from AssemblyScript. The project can be embedded in a website using its JavaScript file and a page element for the emulator. Embed options cover machine selection, zoom, auto-start, tape auto-loading, loading a file by URL and disabling file-opening controls with sandbox mode. JSSpeccy 3 is free and licensed under GPL version 3. The official site credits Matt Westcott as its maker, who describes it as a personal project and makes no commitment to technical support or assistance. Loading a remote file requires the other domain to serve CORS headers.
Who it is for
JSSpeccy 3 suits people who want to run Spectrum 48K, 128K or Pentagon software in a browser, or embed an emulator in a website. It also fits users with supported snapshot or tape files, including files packaged in ZIP archives.
What is good
- Emulates Spectrum 48K, Spectrum 128K and Pentagon machines.
- Supports documented and undocumented Z80 instructions.
- Includes AY and beeper audio.
- Loads snapshot and tape formats, including files in ZIP archives.
- Offers 100%, 200%, 300% and fullscreen display modes.
- Licensed under GPL version 3.
What to know first
- Remote files need their domain to serve CORS headers.
- The maker makes no commitment to technical support or assistance.
Verdict
Pick JSSpeccy 3 if you want a free browser emulator for its three supported Spectrum machines, or need an embeddable emulator with configurable controls. Look elsewhere if you need committed technical support or must load remote files from a domain without CORS headers.
Get started with JSSpeccy 3
- Visit https://jsspeccy.zxdemo.org/.
- Open a supported snapshot or tape image, including one contained in a ZIP archive.
- Choose a display size: 100%, 200%, 300% or fullscreen.
- To embed it, add the project's JavaScript file and a page element for the emulator.
- Configure embed options such as machine, zoom, auto-start or tape auto-loading as needed.
Limits to know first
Loading files from another domain requires that domain to serve CORS headers. The maker makes no commitment to provide technical support or assistance.
Questions about JSSpeccy 3
How much does JSSpeccy 3 cost?
It is free, with a Free plan.
Which machines does it emulate?
It emulates the Spectrum 48K, Spectrum 128K and Pentagon.
Which files can it load?
It loads SZX, Z80 and SNA snapshots, plus TZX and TAP tape images using traps. Supported files can also be loaded from ZIP archives.
Can I embed JSSpeccy 3 in a website?
Yes. The project is designed for embedding with its JavaScript file and a page element for the emulator.
Is JSSpeccy 3 open source?
Yes. It is licensed under GPL version 3.
Who made it, and is support provided?
The official site credits Matt Westcott as the maker. He describes it as a personal project and makes no commitment to technical support or assistance.
Compared on ZX spectrum emulators
- Free plan
- Yes
- Host platforms
- web browser
- Tape formats
- TZX, TAP
- Snapshot formats
- SZX, Z80, SNA
- Open source
- Yes
