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Tech riderRev. 21 Sept 2026

JSSpeccy 3

Ch 206.4of 21 ZX Spectrum Emulators
  1. 1Runs onself-hosted, Web
  2. 2CostsNot stated by the maker
  3. 3Host platformsweb browser
  4. 4Tape formatsTZX, TAP
  5. 5Snapshot formatsSZX, Z80, SNA
  6. 6Open sourceYes
5 lines stated Written from the maker's own pages: jsspeccy.zxdemo.org
Visit site Alternatives
The JSSpeccy 3 homepage

Overview

JSSpeccy 3 is ranked #20 of 21 in ZX spectrum emulators on Specifiction. It runs on Self-hosted, Web.

Compared on ZX spectrum emulators

Free plan
Yesjsspeccy.zxdemo.org
Host platforms
web browserjsspeccy.zxdemo.org
Tape formats
TZX, TAPjsspeccy.zxdemo.org
Snapshot formats
SZX, Z80, SNAjsspeccy.zxdemo.org
Open source
Yesjsspeccy.zxdemo.org

Facts

Purpose
JSSpeccy 3 is a ZX Spectrum emulator that runs in a browser.jsspeccy.zxdemo.org · 4 Oct 2026
Emulated machines
It emulates the Spectrum 48K, Spectrum 128K and Pentagon machines.github.com · 4 Oct 2026
Processor emulation
It handles documented and undocumented Z80 instructions.github.com · 4 Oct 2026
Display accuracy
It provides cycle-accurate emulation of scanline and multicolour effects.github.com · 4 Oct 2026
Audio
It supports AY and beeper audio.github.com · 4 Oct 2026
Supported files
It loads SZX, Z80 and SNA snapshots, plus TZX and TAP tape images via traps, and can load these formats from ZIP files.github.com · 4 Oct 2026
Display modes
It offers 100%, 200%, 300% and fullscreen display modes.github.com · 4 Oct 2026
Implementation
The emulator runs in a Web Worker, with its core compiled to WebAssembly from AssemblyScript.github.com · 4 Oct 2026
Embedding
The project is designed to be embedded in websites using its JavaScript file and a page element for the emulator.github.com · 4 Oct 2026
Remote file loading
Loading files from another domain requires that domain to serve CORS headers.github.com · 4 Oct 2026
License
JSSpeccy 3 is licensed under GPL version 3.github.com · 4 Oct 2026
Support
The maker describes it as a personal project and makes no commitment to provide technical support or assistance.github.com · 4 Oct 2026
Supported machines
It emulates the Spectrum 48K, Spectrum 128K and Pentagon machines.github.com · 4 Oct 2026
Display
It provides cycle-accurate scanline and multicolour effects, with 100%, 200%, 300% and fullscreen display modes.github.com · 4 Oct 2026
File formats
It loads SZX, Z80 and SNA snapshots, plus TZX and TAP tape images using traps; supported files can also be loaded from ZIP archives.github.com · 4 Oct 2026
Configuration
Embed options include machine selection, zoom, auto-start, tape auto-loading, file loading by URL, and disabling file-opening controls with sandbox mode.github.com · 4 Oct 2026
Notable limit
Loading remote files by URL is subject to browser security restrictions; files hosted on another domain need to be served with CORS headers.github.com · 4 Oct 2026
Maker
The official site credits Matt Westcott as the maker.jsspeccy.zxdemo.org · 4 Oct 2026

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