Prism

A fast, universal media viewer for Windows. Open anything, view it beautifully.

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Prism opens an image, a video, an audio file, or a PDF and shows it instantly, then lets you arrow through the rest of the folder without a beat. It is the "quick look" Windows never shipped: one small app that opens everything and looks good doing it.

Early development. See ROADMAP.md for the plan and phases.

What it is

• Images: zoom, pan, fit, rotate, fullscreen; common and exotic formats.

• Video: play / pause / seek / volume / fullscreen, frame-step, and a settings menu with speed, loop, autoplay (the next video in the folder plays itself), and subtitles: sidecar .srt/.vtt files are found by name, next to the file or in Subs/.

• Audio: play with a live circular visualizer; the same settings menu (speed, loop, autoplay the next track).

• PDF: Prism's own viewer, no browser chrome: continuous pages, zoom and fit, text selection, and its own Ctrl+F that counts matches across the whole document.

• Documents: markdown renders formatted (badges, images, even embedded video); plain text stays clean and monospaced.

• Folder aware: open one file, then use the arrow keys to move through its neighbours. Choose whether the arrows stay within media, within documents, or one file type, from the filter in the sidebar or Settings → General.

• File tree (Ctrl+B): a collapsible panel of the folder you opened in. Expand subfolders, click any file to view it. It never reaches above that folder. Right-click for the verbs: open in another app, show in Explorer, copy, duplicate, rename, delete. Drive it entirely from the keyboard: arrows move through folders and files alike, Enter opens or collapses a folder, and files open as you land on them.

• Code, highlighted: source files open with syntax colouring, line numbers, folding and their own Ctrl+F, across ~150 languages. Where the language has a real grammar, a syntax error gets the red underline you would expect from an editor.

• Edit text files in place: any text file is editable where it sits, Ctrl+S to save. Click into the text to get a caret; until you do, the arrow keys keep paging the folder. Markdown keeps a pencil in the top bar, to swap its rendered page for its raw source. Wander off to another file and your edits wait for you: unsaved files are starred in the tree, and nothing closes Prism out from under them.

• Zips are folders: a zip (and a 7z, rar, tar, iso and the rest) keeps its icon but opens like any other folder, in the Explorer and in a project's tree. One address runs through it, Back and Forward walk in and out, and sorting, search and the preview pane work inside it. A strip names the archive with Extract here and Extract to...; the right-click menus are the archive's (extract, add files, rename and delete inside a zip). A file inside opens read-only, unpacked to a temporary folder that is cleared when Prism closes.

• Opens from Explorer: opt in to make Prism the default viewer for the file types you choose.

• In Explorer's right-click menu: beside the Prism icon, Open file on any file and Open as project on a folder, or on the empty space inside one, which roots a tab there. On by default, switched in Settings → General; on Windows 11 the entries sit under "Show more options" (Shift+F10).

• On your phone: More (the three dots) > Phone serves the folder you have open to phones on your own Wi-Fi. Scan the QR code once, then browse the folder on the phone and play video, audio and pictures straight from the PC. The code decides only where you start: the phone lists every folder Prism has open and switches between them without another scan, and a reload comes back to the folder you were in, or the film you were watching. Plain HTTP on your own network, nothing leaves it; the PC lists every paired phone and can forget one at any time. What the phone cannot play as it is (an MKV, HEVC on an Android, Dolby audio) the PC's GPU converts live, HDR tone-mapped, and the phone seeks through it like any other file. PDFs, markdown, code, office and ebook documents, comics and archives open on the phone too, read-only: nothing on the phone can change a file on the PC. Search from the phone with the same box the sidebar has - a couple of words in any order, "a phrase", *.mp4, ext:pdf, -drafts - and a file three folders down is one tap away instead of unreachable, and the list narrows as you type rather than going blank while the PC answers. Films go fullscreen by whatever route the phone actually has, the page itself on Android and an iPhone's own player on iOS. Everything is sized for a thumb, and while a film is playing a tap brings the controls back instead of pausing; the tap after that pauses, the way every phone player behaves. There is one screen, the folder: the phone plays what it opens, and never drives the PC.

• A terminal beside the file (Ctrl+`): a real shell docked to the window, opened in the folder you are viewing, with themes, find, command help and local dictation. It is the same terminal as Prism Terminal, shared code rather than a copy, so a fix in one reaches the other. A file dropped on it types its path, quoted for the shell it goes to.

• Gets back up on its own: if the window's page crashes or hangs, Prism reloads it, and a window that keeps failing is rebuilt. Opening a file always brings up a working window. Crash reports stay on your PC (in Prism's own folder under %APPDATA%) and are never uploaded anywhere.

• Opens instantly, every time: the Explorer shows the folder you left, even right after a restart, because it keeps a small list of what is in the folders you open (file names, sizes and dates). That list stays on your PC, under Prism's own folder in %APPDATA%, is never sent anywhere, and is never kept for network or removable drives. Turn it off or clear it in Settings → General → Remember folders.

Prism is a viewer, not a library or editor. It stays fast, quiet, and out of the way.

Shared engine

Prism's viewer is a standalone package, prism-core, which also powers the previews inside Filesmith. One engine, two apps, no duplicated code. Neither app needs the other installed.

Install

Download Prism-Setup-x64-<version>.exe from Releases and run it (per-user, no admin). The installer is unsigned, so Windows SmartScreen may warn on first run: More info → Run anyway.

Build from source

Requires Node.js 20+ and Windows.

npm install
npm run dev        # launch with hot reload
npm run typecheck  # tsc project checks
npm run lint       # eslint
npm test           # unit tests (vitest)
npm run package    # build the Windows installer into dist/

npm run package (and npm run e2e) first runs npm run fetch:bin, which downloads the three binaries Prism bundles into vendor/ and verifies each against a pinned SHA-256. They are not in git; the fetch is a one-off per clone.

Stack: Electron + TypeScript, React + Vite + Tailwind v4. See CLAUDE.md for architecture and scope.

Third-party

Prism bundles three programs in resources/bin, each used unmodified, as a separate program, and each fetched at build time from a pinned release (see tools/fetch-*.mjs).

• ffmpeg (BtbN LGPL shared build, LGPL v2.1+) - decodes the audio Chromium will not (Dolby Digital, DTS, TrueHD), converts video it cannot show (MPEG-2, Xvid, WMV, ProRes), and reads the stills it cannot draw. The shared build is deliberate: its DLLs can be replaced with your own build of the same libraries. Licence at resources/bin/LICENSE.txt.
• 7-Zip (LGPL, with the unRAR restriction on its rar code) - lists and extracts 7z, rar, tar, gz and the rest. Licence at resources/bin/License.txt.
• FluidSynth (LGPL v2.1) with the FluidR3Mono General MIDI soundfont (MIT, Frank Wen; mono conversion by Michael Cowgill) - synthesises MIDI, which is a score rather than a recording. Licences at resources/bin/LICENSE-fluidsynth.txt and resources/bin/LICENSE-soundfont.md.

The full list of what Prism ships, with each component's licence and where its text lives, is in THIRD-PARTY-NOTICES.md.

License

Prism is proprietary. Copyright (c) 2026 Max Aubert, all rights reserved. The source code may not be used, copied, modified or redistributed without written permission; official binaries are free to install and use, personally or inside an organisation. See LICENSE.

Releases published on or before 2026-10-03 (up to v0.79.1) were issued under the MIT licence, and that grant still covers those versions. It does not extend to anything after them.

Third-party components and their licences are listed in THIRD-PARTY-NOTICES.md.

Commercial licensing enquiries: aubert@post.com