JSNES vs Nestopia Undead Edition

JSNES is a free JavaScript library for emulating NES games in browsers and Node.js. Its Browser helper handles canvas rendering, audio, keyboard and gamepad input, and frame timing; the lower-level NES class allows custom rendering and audio handling in Node.js. ROM data can be loaded from a URL or from a string, Uint8Array, or ArrayBuffer. The API runs frames, accepts controller input for either player, resets, adjusts frame rate, and includes methods for moving and triggering the Zapper. Applications can serialize and restore emulator state with `toJSON()` and `fromJSON()`. The `onBatteryRamWrite` callback lets an application capture battery-backed SRAM writes for persistent game saves. Sound emulation is enabled by default, with a default sample rate of 48000 Hz, and an audio callback is available. The README provides npm installation for Node.js or Webpack and an unpkg script for browser use, as well as a React embedding example. JSNES is licensed under Apache-2.0; its GitHub Issues tracker accepts bug reports and feature requests.

Nestopia Undead Edition is a free graphical interface project for the Nestopia emulator, aiming to provide a standalone GUI. The maker’s site lists version 1.99.0 as released, and the project identifies its license as GPL-2.0. The product platform listing names Linux, macOS and Windows, while the supported-platform listing names Windows. The repository includes source required to build the legacy Win32 release; for future GUI work, it points to a cross-platform build under the Jolly Good Emulation project. Nestopia UE supports save states, rewind, netplay, shader support and cheats. For a Nestopia-format cheat database, the project points users to Mighty Mo’s Cheat Code Pack. The project no longer maintains the emulator core and directs core emulation issues upstream. Contributions are reviewed when they relate to standalone GUI builds. Code outside a tagged release is described as volatile, so development work not included in a tagged release may change. The listed plan is free, with no stated price or usage limits.