Software that is specifically made to run on an Ultimate Device. Meaning a 1541Ultimate, Ultimate II+, Ultimate Elite, or a Commodore64 Ultimate.

• ReadyOS - What if a Commodore 64 could feel ready, not just nostalgic? ReadyOS treats waiting as the enemy. It is a keyboard-first, full-screen terminal-style environment built around instant app switching, suspend/resume, shared clipboard and history, and deeper links between apps.
• Command64 OS - MS-DOS style operating system for the C64 with a REU size of 1MB minimum

• geoIRC - IRC client for GEOS/GDOS64. Connect to any IRC channel available on the internet. Only works via Ethernet!
• GeoUTools - Tools for use with Ultimate devices without having to leave the GUI, or even having to open the Ultimate menu! Also works in 80-column mode in GEOS128 with Ultimate cartridge.

• SID-Wizard 1.97 - SID tracker for Commodore 64/128 as well as for Windows, MacOS, and Linux. Create music for up to 4 SID chips (real, or virtual). Includes a large instrument library, example tracks, MIDI, and a piano roll view.

• C64UHEX - C64UHEX is a native hex editor for the Commodore 64. It provides professional, byte-level inspection and modification of binary data using a true PETSCII interface, respecting the constraints and character semantics of the original platform.
• AdvEditC64 - Advanced Commodore Editor - Advanced Commodore Editor is a native, full-screen text editor designed specifically for the Commodore 64, with special attention given to the C64 Ultimate and its SD/USB-based storage workflow. The editor is inspired by the philosophy of the Linux nano editor: Simple controls, fast interaction, minimal cognitive overhead, and clear on-screen prompts while respecting the technical constraints and historical behavior of vintage hardware.

Games specifically created to make use of the features of an Ultimate device.

• No known games at the time of this writing

• Infinite Matter
• Ultiverzum
• The Tuneful Eight (included on The Very Second)
• UltimateDemo2026
• Raster Split Fun

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  Ultimate Opus

  Ultimate Opus - A dual-pane file manager for Ultimate devices, released by Lft. Current version is 0.2, released in 2014. No active development.

• UBoot64-v2 - Boot manager/Boot menu for Ultimate devices.

Software that is specifically made to run on a computer other than the C64 or C128. The software below is designed for use WITH but not ON an Ultimate device.

Remote control applications that enable viewing, playing, copying, and otherwise interacting with a system from another computer.

• C64 Ultimate Viewer for Linux - A simple video & audio stream viewer designed for the new C64 Ultimate owners running Linux systems. Watch your C64 screen output on your computer with real-time streaming.
• U64 Remote cpp - Remotely send and run a .PRG file on a Commodore 64 Ultimate. A Linux C++ command-line client for interacting with the Commodore 64 Ultimate over its REST API. This project is a C++ port of the original Go reference implementation and allows remote control and inspection of a C64 Ultimate from a modern Linux system.
• Ultimate64 Manager - A cross-platform desktop application for managing Commodore 64 Ultimate, Ultimate 64 Elite, and Ultimate-II+ devices. Browse files, stream content, play SID music, mount disk images, and configure device settings. Also, 'Memory Editor', you can now peek and poke C64 memory directly from your desktop.
  • Amiga OS version
  • iPhone version
• U64 Remote - Remotely send and run a .PRG file on any Ultimate device.

• Commodore C64 Ultimate CLI - A MacOS/Linux/Windows command-line interface for controlling the Commodore C64 Ultimate via its REST API.
• MCP server for the Ultimate 64 series ! Version 0.1 Alpha ! - A Model Context Protocol (MCP) server for the Commodore 64 Ultimate — the official modern Commodore 64 computer. This server enables AI assistants like Claude, ChatGPT, and Cursor to control your C64 via the Ultimate's REST API.

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  Ultimate 64 Web Music Player on a mobile device

  Ultimate 64 Web Music Player - Use any device with a web browser to play your favorite SID songs at home. Designed to be used with your mobile phone to have an easy way to control the music that is coming out of your C64 or C64U.

• Ultimate64 SID Player (Windows/Mac/Linux) - Play SID music files from your Commodore 64 Ultimate, Ultimate64, or Ultimate-II+ via the REST API.
• Phosphor - A SID music player for USBSID-Pico hardware, software-emulated SID, and for Commodore Ultimate 64 network playback. Includes a library panel for finding music online off the HVSC website.
• Ultimate64 SID Player (Amiga) - Ultimate64 SID Player is a full-featured C64 SID music player for AmigaOS that connects to Ultimate64 and Ultimate-II devices over the network. It provides playlist management, multi-subsong navigation, and integrates with the HVSC song length database for accurate playback timing.

• ALBERT - Win/Mac/Linux application to create C64 graphics, it can send its images to your Ultimate device, save them as .PRG and other formats. ALBERT allows its users to create Commodore 64 images that extend into the left and right borders of the visible screen, with sprites to display the extra pixels, using an uncomplicated drawing workflow, without requiring the assistance of a coder.

Tools to prepare data on an other computer before moving it over to the C64U to be used there.

• GameBase64 Game Organizer - A Python utility to organize Commodore 64 games from zip archives into a structured folder hierarchy based on metadata from VERSION.NFO files.