JNEXT
What it is
JNEXT is a free, open-source emulator for running ZX Spectrum software on Linux, macOS, and Windows. It supports 48K, 128K, +2A/+3, and ZX Spectrum Next Issue 2 machines. Its developer-focused debugger includes hardware views, registers, breakpoints, and backward execution. Headless mode and deterministic screenshots support program testing in continuous integration. Supported files include NEX, SNA, SZX, Z80, TAP, TZX, WAV, and RZX. The emulated hardware includes three AY chips, a DAC, and a beeper, with peripherals such as DivMMC, DMA, USB gamepads, and the ESP-01 WiFi module; networking is off by default. If no NextZXOS image is configured, JNEXT can download the official SD-card image on first run. The original and working images together use about 2 GB of disk space. The software is licensed under GPLv3. The project remains under development and does not aim for extreme cycle-exactness. Its Windows executable is unsigned, and its macOS app is not notarized, which can affect first launch.
For and against
For
- Free software under GPLv3.
- Debugger includes breakpoints and backward execution.
- Headless mode supports CI testing.
- Supports several tape and snapshot formats.
- Packages are offered for Linux, Windows, and macOS.
Against
- The project is still under development.
- Extreme cycle-exactness is not a goal.
- Windows executable is not code-signed.
- macOS app is not notarized.
The verdict
JNEXT pairs broad ZX Spectrum machine support with debugging and automation features. Account for its development status and operating-system launch warnings when deciding whether it fits your setup.
Who it suits
JNEXT may suit developers who need ZX Spectrum emulation with debugging and CI testing tools. It also supports ordinary program use across Linux, Windows, and macOS.
Plans and prices
Free software
No ads · Nothing for sale · GPLv3
Read 30 Sep 2026 · jnext.es
On the record
- Audience
- The user guide covers ordinary program use and also developer tools, debugging, and automation in CI.jnext.es · read 30 Sep 2026
- Audio and peripherals
- The emulator includes three AY chips, a DAC, a beeper, and support for peripherals including DivMMC, DMA, and USB gamepads.github.com · read 29 Sep 2026
- Automation
- JNEXT supports headless mode and deterministic screenshots for testing programs in CI.github.com · read 29 Sep 2026
- Debugger
- Its debugger includes hardware views, registers, breakpoints, and backward execution.jnext.es · read 29 Sep 2026
- Downloads
- Packages are offered for Linux, Windows, and macOS, with Linux packages including deb, rpm, and Flatpak.jnext.es · read 29 Sep 2026
- Emulated machines
- It emulates ZX Spectrum 48K, 128K, +2A/+3, and ZX Spectrum Next (Issue 2).jnext.es · read 30 Sep 2026
- Emulation
- It emulates 48K, 128K, +3, and ZX Spectrum Next Issue 2 machines.github.com · read 29 Sep 2026
- File formats
- Supported formats listed include NEX, SNA, SZX, Z80, TAP, TZX, WAV, and RZX.jnext.es · read 30 Sep 2026
- Image storage limit
- The downloaded original and working SD-card image together take about 2 GB of disk space.jnext.es · read 30 Sep 2026
- Known limits
- The project says it is still under development, and extreme cycle-exactness is not a goal.github.com · read 29 Sep 2026
- License
- JNEXT is free software under the GPLv3 license.jnext.es · read 29 Sep 2026
- License and maker
- JNEXT is free software under GPLv3 by Jorge Gonzalez (ZXjogv), and the site says it is not affiliated with SpecNext Ltd.jnext.es · read 30 Sep 2026
- macOS notarization
- The macOS app is ad-hoc signed but not notarized, so Gatekeeper blocks its first launch.github.com · read 29 Sep 2026
- Networking
- JNEXT emulates the ESP-01 WiFi module so Next software can reach the real network; networking is off by default.jnext.es · read 30 Sep 2026
- Operating system image
- The Next boots NextZXOS from an SD-card image, and JNEXT can download the official distribution image on first run if none is configured.jnext.es · read 30 Sep 2026
- Privacy
- The site says it has no ads and no trackers beyond a self-hosted page counter.jnext.es · read 29 Sep 2026
- Privacy and funding
- The site says JNEXT has no ads, nothing for sale, and no trackers beyond a self-hosted page counter.jnext.es · read 30 Sep 2026
- Product
- JNEXT is an open source emulator for running ZX Spectrum Next software in real time, with a developer focused view of the machine.jnext.es · read 30 Sep 2026
