You want a short animated video for your channel, and the usual routes both disappoint. An AI video generator gives you pretty clips that drift: the character changes face halfway through, the physics looks wrong, and you cannot fix one bad second without re-rolling the whole thing. This guide covers a third route — how to make viral animated shorts with Claude Code — using a free skill that treats a short as code: a script, a shot plan, a painted 3D town, flat cartoon characters, and a render you can re-run frame for frame.

One word of honesty first. "Viral" here is the skill author's framing, borrowed from the video it came from, "How to Make Viral Animated Shorts Using Claude (Full Workflow)". Nothing in the repository promises views, and this guide does not either. What the skill does promise, backed by its one proven example, is a repeatable pipeline: the same short, rendered twice, comes out the same twice, and a single bad shot can be fixed without throwing the rest away.

What Claude Animated Shorts is

Claude Animated Shorts is a free, MIT-licensed Claude Code skill that makes 55–70 second vertical animated story shorts: 2D characters in a colourful 3D world, rendered with three.js inside Remotion on your own PC, with no AI video generator. Nothing is generated as video. The world is built in code, the characters are drawn in code, the cameras glide on keys you can read, and the sound is synthesized in code. If a shot looks wrong, you change a number, not a prompt, and re-render.

The look is specific, and the skill is honest about where it came from. Its author studied 20 reference shorts from one channel, frame by frame, and wrote the measurements down: a style bible, seven reports, 38 full-size reference frames, and 20 contact sheets of 60 frames each. The result is a formula you can name: flat bean-head cartoon cards with ink outlines, a painted 3D town with black ink lines, a saturated sky, depth-of-field backgrounds, gliding cameras, voice narration, and synthesized sound effects plus march-style music. Boundary: the reference frames are style study only — never upload, publish, or send them, story, characters, and voice must always be your own, and never name the channel in a voice-over or description.

The skill's one proven example is "The Bridge That Fell for a Song", a 67-second original short about the 1831 Broughton bridge and 74 soldiers marching in step. The story works because it follows the skill's beat formula: an absurd hook in one line, the setting, an escalation over three or four beats, the snap, a deadpan double line, one physics idea explained through an everyday analogy (a kid on a swing), the rule the disaster created, and a callback twist. Pick a surprising true story with a physical cause and effect, and the formula does the rest of the shaping.

Install and use

The commands below are quoted verbatim from the README and SKILL.md; they were not executed in this run, so verify them on your machine.

First, the requirements from the README: Remotion with @remotion/three, plus Node, Python 3, and ffmpeg. Install is a copy, not a marketplace plugin: clone or download the repository, then copy the folder to ~/.claude/skills/cartoon-3d-short/.

git clone https://github.com/mromidev/claude-animated-shorts

Then, in Claude Code, say:

Use the cartoon short skill and make a short about …

Claude then follows SKILL.md in order: topic and facts, then script, then voice, then the shot plan in story.ts, then stills, then renders. Write the facts with their source at the top of SCRIPT.md first, then the script at about 3.7 words per second for a 55–70 second short. Record or generate voice.wav, then build its word timings as words.json — and hand-fix those timings, because everything downstream is timed to them. Only then copy templates/bridge/ to src/videos/<name>/, register a new composition next to BridgeShort in src/Root.tsx, and plan the shots (frames, light, crowd mode, crossfades, camera keys, lens blur, foreground props). Every visual reaction must land zero to three frames before its word.

Before the final render, the skill insists on look checks. Render stills and compare them side by side against the reference frames:

node scripts/bridge-stills.mjs out/<name>/x_ 100,400 0.5

Send the sheets to a verifier agent — the skill specifies an Opus max verifier — for a verdict of 200 words or fewer, fix what it finds, and only then render. The bridge short went through four verifier rounds; expect the same loop on your first short.

The final render exports 2K vertical video:

npx remotion render src/index.ts <Comp> out/<name>/video.mp4 --codec h264 --crf 16 --scale 1.3333

Remotion writes a silent audio track, so mux the real mix with -map 0:v:0 -map 1:a:0. Then run the QA script, which checks every frame for black, white, frozen, and pop frames, plus loudness and sheets:

python scripts/short_qa.py final.mp4 out/<name>/qa shots.json

Where it fits, and where it does not

This skill fits best when you want a repeatable house style for short-form history or science stories: one surprising true story per short, the same cartoon look every time, and a pipeline where a correction means editing code and re-rendering, not re-rolling a generator. It fits creators who are comfortable in a terminal and willing to babysit a render. Age caution: created 2026-11-01, only two commits, 1,257 stars on 2026-11-04 — treat the bridge short as a template to adapt, not proof every story works first time.

It does not fit every video idea. The user rules in SKILL.md are narrow: no captions or labels in the video, English only, one steady voice tone, and a standard mix of music +3 dB, SFX −6 dB, voice unchanged. If you need captions for accessibility, a non-English voice, or a different tone per scene, you will be fighting the template. It is not a general video editor, it does not generate footage, and it will not rescue a weak story.

Three practical cautions, all from the skill's own notes. First, time: 2K renders run at about 4 frames per second, roughly 10 minutes for a 67-second short. Second, disk: every Remotion bundle copies public/ (about 1.3 GB) into the temp folder and never deletes it — the author reports 60+ GB filling a system drive during the bridge passes, so set REMOTION_TMP to a folder on a big drive before you start. Third, sound is locked to picture: lock the picture's time constants before making the sound, because any later timing change means re-running the sound.

FAQ

How do I make viral animated shorts with Claude Code? Use the Claude Animated Shorts skill: clone the repository, copy it to ~/.claude/skills/cartoon-3d-short/, and in Claude Code say "Use the cartoon short skill and make a short about …". Pick one surprising true story, follow the beat formula (hook, escalation, snap, explanation through an everyday analogy, callback twist), and render with three.js inside Remotion. "Viral" is the author's framing, not a promised outcome.

How do I install the Claude Animated Shorts skill? Clone https://github.com/mromidev/claude-animated-shorts and copy the folder to ~/.claude/skills/cartoon-3d-short/ (or download the ZIP). You need Remotion with @remotion/three, Node, Python 3, and ffmpeg. There is no marketplace install command in the README, and the commands in this guide were quoted, not executed.

How do you make animated shorts with three.js and Remotion? Build the world and characters as code, plan shots in story.ts, render stills and compare them against measured reference frames, then render the final MP4 with npx remotion render src/index.ts <Comp> out/<name>/video.mp4 --codec h264 --crf 16 --scale 1.3333. The composition is 1080x1920 at 30 fps, exported at 2K vertical (1440x2560).

Does Claude Animated Shorts use an AI video generator? No. Everything is rendered with three.js inside Remotion on your own PC: the painted town, the cartoon character cards, the gliding cameras, and the synthesized sound. No generated footage means no face drift and no re-rolling — but you do the work of scripting, timing, and fixing shots.

Can I copy the style of a channel I like with this skill? Only in the narrow sense the repository allows: study the look's measurements and build your own story, characters, and voice in that style. Its reference frames are style study only — never upload, publish, or send them, never copy the reference channel's scripts, characters, or shots, and never name the channel in a voice-over or description.

How long does a Claude animated short take to render? According to SKILL.md, 2K renders run at about 4 frames per second, roughly 10 minutes for a 67-second short. Budget extra time for the look-check loop, and set REMOTION_TMP to a big drive first — Remotion bundles are about 1.3 GB each and are never auto-deleted.

See the skill's directory entry for install, platforms, and quick start: Claude Animated Shorts on aiskills.one.