JSSpeccy 3 review
Free, open-source browser emulation with accurate timing and broad file support.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
JSSpeccy 3 is a browser-based ZX Spectrum emulator by Matt Westcott for people who want to run Spectrum software without a desktop installation. It emulates 48K, 128K, and Pentagon machines, handles documented and undocumented Z80 instructions, and supports cycle-accurate scanline and multicolour effects. Audio support includes AY and beeper sound, while display options include fullscreen plus 100%, 200%, and 300% modes. It is also distributed under the GNU General Public License version 3, making it relevant to developers and preservation projects that value open-source access.
The pricing model is straightforward: JSSpeccy 3 is free and open source, with no paid tiers described. Its platform fit is similarly focused. The emulator runs in a web browser and can load SZX, Z80, and SNA snapshots, TZX and TAP tape images, and supported files packaged in ZIP archives. JavaScript embedding and control APIs extend its usefulness beyond individual play sessions, allowing websites and software projects to place an emulator into a broader browser experience. Tape loading is described as trap-based, which is a specific implementation detail for buyers assessing compatibility.
JSSpeccy 3 is a strong choice for instant browser-based emulation, embedded demonstrations, and lightweight Spectrum access across the supported machines and file formats. Its cycle-accurate timing and multicolour effects give the project meaningful depth rather than limiting it to basic snapshot playback. The trade-off is scope: its documented machine coverage does not include Spectrum +2 or +3, and its model, peripheral, and debugging coverage is narrower than desktop alternatives. Choose it when browser delivery, open-source licensing, and JavaScript control matter most; choose a broader desktop emulator when expanded hardware or debugging support is central.
JSSpeccy 3 pros and cons
- Where it wins
- Runs 48K, 128K, and Pentagon Spectrum machines in a browser
- Cycle-accurate scanline and multicolour effects with AY and beeper audio
- Loads snapshots, tape images, and supported files from ZIP archives
- Where it doesn't
- Web-browser access only; there is no desktop platform
- Spectrum +2 and +3 are outside its documented machine support
- Narrower peripheral and debugging coverage than desktop alternatives
JSSpeccy 3 fact sheet, pricing and score →
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