JNEXT

Overview

JNEXT is a free ZX Spectrum emulator for running software from classic Spectrum machines through the ZX Spectrum Next. It suits developers who want debugging and CI automation alongside emulation, as well as users exploring Next software. Its broad machine and peripheral support is compelling, though the project’s development status and launch warnings call for some patience.

JNEXT is GPLv3 software by Jorge Gonzalez (ZXjogv), and its maker says it is not affiliated with SpecNext Ltd. It runs on Linux, Windows, and macOS. The project is still under development and does not target extreme cycle-exactness, so it is a weaker fit for work that depends on precise hardware timing. Questions and bug reports go to the GitHub issue tracker.

Key features

Machines and hardware

JNEXT emulates the 48K, 128K, +2A/+3, and ZX Spectrum Next Issue 2. It covers ULA and Timex video modes, Layer 2, 128 hardware sprites, tilemap, and Copper, with three AY-3-8910 chips, a DAC, and a beeper for audio. This range makes it useful for developers working across generations, not just Next titles.

Peripheral support includes DivMMC and SD card, Multiface, DMA, UART, CTC, SPI/I²C, a real-time clock, keyboard, USB gamepads, and Kempston mouse. JNEXT also emulates the ESP-01 WiFi module, allowing Next software to reach the real network; networking is off by default. On first run, it can download the official NextZXOS distribution image if no SD-card image is configured. The original and working images together use about 2 GB of disk space.

Development and media tools

The debugger provides hardware views, registers, breakpoints, and backward execution. That makes JNEXT a more focused choice for inspecting and debugging programs than an emulator aimed only at launching software. Headless mode and deterministic screenshots support CI testing, while RZX session playback can reproduce user input alongside a machine snapshot, provided the replay emulator models the machine the same way.

It supports NEX, SNA, SZX, and Z80 snapshots, plus TAP, TZX, and WAV tape formats. JNEXT can record audio to WAV without ffmpeg or a sound card; MP4 video with audio requires ffmpeg. Those options suit testing and recording workflows, though video capture has an external dependency.

Pricing

JNEXT is free software under GPLv3. The Free software plan costs 0.00 USD per free and includes no ads and nothing for sale. There is no free trial because the software is free. There are no paid tiers or plan-based feature reductions to weigh.

Platforms

JNEXT has packages for Linux, Windows, and macOS; Linux packages include deb, rpm, and Flatpak. Windows executables are not code-signed, and SmartScreen may warn that the publisher is unrecognized. The macOS app is ad-hoc signed but not notarized, so Gatekeeper blocks its first launch. These warnings add friction during installation, especially for users expecting a conventional signed release.

The maker says JNEXT has no ads and no trackers beyond a self-hosted page counter.

Who it's for

Choose JNEXT if you want ZX Spectrum Next support alongside earlier machines, or need a debugger and deterministic screenshots for development and CI. Its peripheral coverage, file-format support, and headless mode give developers several ways to work with programs beyond interactive use. Users who prioritize extreme timing accuracy, or want a polished first-launch experience on Windows or macOS, should consider its stated limits and launch blockers before settling on it.

Pros and cons

• Pros: Emulates four Spectrum generations, including Next Issue 2, with broad video, audio, and peripheral coverage.
• Pros: Free GPLv3 software with no ads or products for sale.
• Cons: Extreme cycle-exactness is not a goal, ruling it out for some timing-sensitive work.
• Cons: Windows SmartScreen warnings and macOS Gatekeeper blocking make first launch less direct.
• Cons: The downloaded and working SD-card images together take about 2 GB, and MP4 recording depends on ffmpeg.

Alternatives

ZX Spectrum Emulators is a category starting point for comparing options. Unreal Speccy Portable is another free, open-source option if Android support matters alongside Linux, macOS, and Windows. ZEsarUX is also free and open source, with self-hosted support among its platforms. Choose CSpect if you prefer a name-your-own-price option and can accept no support or warranty and no guaranteed updates. Spectral is a free, open-source, experimental emulator whose code is prone to change. EightyOne is a free, open-source Windows-only alternative. GZX is free and open source for Linux and Windows, with ZX Spectrum ROM files excepted from its MIT-style license. Atari 5200DS is another free option. Zedex is a free, open-source option for Android.

Verdict

JNEXT is a strong fit for ZX Spectrum Next developers who want broad hardware emulation, a built-in debugger, and CI-friendly automation without paying for software. Its multiple machine generations and recording options also make it useful beyond development. Look elsewhere if extreme cycle accuracy is essential, or if unsigned and unnotarized app warnings would make setup unacceptable.