Emulators of computers (mostly 8-bit) and consoles in JavaScript / HTML5 online.
Sinclair
- JSSpeccy by Matt Westcott – ZX Spectrum
- js-zx8x by Viachaslau Tratsiak – ZX80
- Qaop/JS by Jan Bobrowski – ZX Spectrum
- ZX Dream by Evgeny Zeyler – ZX Spectrum
- Jtyone by Simon Holdsworth – ZX81
- R.A.Z.E. by Rodrigo Rivas Costa – ZX Spectrum
Commodore
- vic20chrome by Matt Dawson – VIC-20
- SAE by Rupert Hausberger – Amiga
- pet2001 by Thomas Skibo – Commodore PET
- pet by Norbert Landsteiner – Commodore PET
- CLCD by Gabor Lenart – Commodore LCD
Atari
- EstyJS by Darren Coles – Atari ST
- jsA8E by Sascha Springer – Atari 800 XL
- Javatari by Paulo Augusto Peccin – Atari 2600
- JS7800 by Chris Smith – Atari 7800
Apple
- apple1 by Will Scullin – Apple I
- Apple//jse by Will Scullin – Apple IIe
- Apple 2+ by Thomas Skibo – Apple II+
- a2 by David Caldwell – Apple II+
- PCE.js by James Friend – Macintosh
Tandy
- trs80 by Peter Phillips – TRS-80 Model III
- mc-10 by Mike Tinnes – TRS-80 MC-10
- JS Mocha by Brad Grier – TRS-80 CoCo 2
Acorn
- ElkJS by Darren Coles – Acorn Electron
- JSBeeb by Matt Godbolt – BBC micro
- atom by Phil Mainwaring – Acorn Atom
Sega
- Miracle by Matt Godbolt – Sega Master System
- jsSMS by Guillaume Marty – also SMS
Nintendo
- hikey by Lionel Lemarié – GameBoy
- GBA.js by Jeffrey Pfau – GBA
- IodineGBA by Grant Galitz – GBA
- JSNES by Ben Firshman – NES
- nes-js by Takahiro Aoyagi – NES
- CycloaJS – NES
- NesNes by Koen Kivits – NES
- 1964js by Joel Middendorf – also N64
- n64js by Paul Holden – Nintendo 64
Running Unices
- jslinux by Fabrice Bellard – Linux/PC
- jor1k by Sebastian Macke – Linux/OR1000
- pdp11 by Julius Schmidt – DEC PDP-11
- pdp11-js by Takahiro Aoyagi – Unix V6/PDP11
- pdp11 by Paul Nankervis – PDP-11/70
- see also v86 below
Miscellaneous
- WebMSX by Paulo Augusto Peccin – MSX
- ccemu by Jim Battle – Compucolor II
- Galaksija by Dragoljub Obradović – Galaksija
- KC85 Emu by Alexander Lang – Robotron KC 85
- PCjs by Jeff Parsons – IBM PC, Ohio Sc., 8080
- v86 by Fabian Hemmer – PC/x86 (various)
- NanoWasp by Dave Churchill – MicroBee
- jspspemu by Carlos Ballesteros Velasco – PSP
- Orao Emulator by Hrvoje Čavrak – Orao
- js8080 by Chris Double – arcade/8080
- rk86 by Alexander Demin – Радио 86РК
- PK-01 Lvov – ПК-01 Львов
- Cosmac by Maciej Szyc – Cosmac Elf
- DCMO5 by Daniel Coulom – Thomson MO5
- Oberon Emulator by Michael Schierl – Oberon
- S2JS Altair by Ian Davies – Altair 8800
- JSVecX – Vectrex
- Emu8080 by Stefan Tramm – CP/M
- Spacewar by Norbert Landsteiner – also PDP-1
- Spacewar – DEC PDP-1 (Spacewar)