FableCut

FableCut is an open-source, Premiere-style non-linear video editor that runs entirely in the browser and exposes its entire timeline as a single JSON document. Built by ronak-create and released under the MIT license, it is designed from the ground up to be operated by AI agents — including Claude Code and Claude Desktop — while a human watches the timeline update live. The project has no npm dependencies and starts with a single node server.js command.

What It Is

FableCut sits at the intersection of a capable browser video editor and an AI-agent control surface. The core idea, as the README describes it, is that "the project file is the interface": project.json describes media, clips, tracks, effects, keyframes, and transitions, and any process that can write JSON can edit video. The open browser UI hot-reloads within approximately 150 ms via server-sent events, so a human and an agent can work on the same timeline simultaneously. It supports 4 video tracks and 3 audio tracks, drag/trim/split/snap, undo/redo, multi-select, beat and cue markers, real decoded audio waveforms, and canvas aspect presets for 16:9, 9:16 reels, 4:5, and 1:1.

AI Agent Control Surfaces

FableCut exposes three equivalent ways for an agent to drive the editor:

• MCP server — a bundled, zero-dependency stdio MCP server registers with Claude Code or Claude Desktop via one command. Tools include fablecut_status, fablecut_docs, fablecut_get_project, fablecut_set_project, fablecut_patch_project, fablecut_import_media, and fablecut_analyze_reference. The surface is described as "token-efficient by design": agents patch the timeline with small ops rather than round-tripping the whole document.
• Direct file editing — read project.json, modify, bump the revision counter, write. The UI live-reloads automatically.
• REST API — GET/PUT /api/project, POST /api/upload, GET /api/library, and a server-sent events stream at /api/events.

Conflict-safe concurrent editing is built in: a revision counter causes conflicting writes to return a 409 instead of silently overwriting changes, and the UI surfaces agent-write conflicts as a toast notification.

Visual and Motion Capabilities

Beyond the agent-first architecture, FableCut ships a substantial set of editing features:

• Look: 12 one-click filter presets (cinematic, teal-orange, noir, vintage, cyberpunk), adjustment layers, full grade controls (brightness/contrast/saturation/hue, temperature/tint, blur, vignette, animated film grain), blend modes, per-edge cropping, corner radius, flip H/V, chroma key with spill suppression, and in-browser AI background removal via MediaPipe.
• Motion: keyframe animation on ~25 properties with easing, speed ramps with time-remapped audio, camera shake, RGB-split/chromatic aberration, and 17 transitions including glitch and pop.
• Text: kinetic captions (typewriter, word-pop, word-slide, karaoke, letter-pop, wave, bounce, shake), neon glow, Google Fonts loaded by name, gradient fills, outline, background pills, and soft shadows.
• Animated SVG clips: a first-class svg clip kind where CSS @keyframes-animated SVGs render frame-accurately in preview and export; agents can author their own vector overlays as plain .svg files.

Reference Video Remake

A standout feature is the reference-video analyzer (analyze.js / POST /api/analyze / fablecut_analyze_reference MCP tool). Given a reference edit, it returns an edit blueprint: shot boundaries, music beats and BPM, a loudness curve, per-shot energy, the drop, and the reference's music track extracted into the project's media folder. The README describes the workflow as: give an agent a reference reel, have it call fablecut_analyze_reference, receive the blueprint, and rebuild the structure shot-for-shot with the user's own footage. This requires no extra dependencies beyond ffmpeg for decoding.

Update: v1.3.0 — Reference Remake + Demo Video

The latest release, v1.3.0 (published 2026-07-09), is titled "FableCut v1.3.0 — reference remake + demo video," indicating the reference-video analysis and remake workflow is a recent addition to the project. The repository was created in July 2026 and last pushed on 2026-07-09, showing active early development. The project had accumulated 315 stars and 18 forks within days of creation, reflecting strong early community interest in the AI-agent-driven editing concept.