JNEXT is a free, open-source emulator for running ZX Spectrum software, including 48K, 128K, +2A/+3 and ZX Spectrum Next Issue 2 machines. It is built for both ordinary program use and developer workflows. Its debugger offers hardware views, registers, breakpoints and backward execution, while headless mode and deterministic screenshots support testing programs in CI. Emulated hardware includes ULA and Timex video modes, Layer 2, sprites, tilemaps, Copper, three AY chips, a DAC and a beeper. Peripheral support includes DivMMC, SD card, Multiface, DMA, UART, CTC, SPI/I²C, real-time clock and USB gamepads. JNEXT can emulate an ESP-01 WiFi module for network access, which is off by default. It supports NEX, SNA, SZX, Z80, TAP, TZX, WAV and RZX formats. On first run, it can download the official NextZXOS SD-card image if none is configured; the original and working images together use about 2 GB of disk space. Packages are offered for Linux, Windows and macOS under GPLv3. The project remains under development and does not target extreme cycle-exactness.
Who it is for
JNEXT suits ZX Spectrum Next users and developers who want debugging and CI automation tools. It is available on Linux, Windows and macOS.
What is good
- Debugger includes registers, breakpoints and backward execution.
- Headless mode and deterministic screenshots support CI testing.
- Supports a broad range of tape and snapshot formats.
- Free software under GPLv3.
What to know first
- The project is still under development.
- Extreme cycle-exactness is not a goal.
- macOS app is not notarized and Gatekeeper blocks first launch.
- Windows executable is unsigned and may trigger a SmartScreen warning.
Verdict
JNEXT pairs ZX Spectrum emulation with debugging and automation features across desktop platforms. Its development status and platform launch warnings are useful to know before installing.
JNEXT plans and pricing
All plansCompared on ZX spectrum emulators
- Free plan
- Yes
- Host platforms
- Linux, Windows, macOS
- Tape formats
- TAP, TZX, WAV
- Snapshot formats
- NEX, SNA, SZX, Z80
- Built-in debugger
- Yes
- Open source
- Yes
- Peripheral support
- DivMMC, SD card, Multiface, DMA, UART, CTC, SPI, I²C, real-time clock, keyboard, USB gamepads, Kempston mouse, ESP-01 WiFi module