VRChat SDK3 / Avatars 3.0 · Rust monorepo · MIT or Unlicense

Tools for the files a VRChat avatar is made of.

avatar reads, diagnoses, fixes, lints, generates, and previews the binary FBX and Unity YAML an SDK3 avatar is built from — then drives the uploaded avatar over OSC. No Unity in the loop until you build & upload; every command runs offline and takes --json.

Try the inspector in your browser Quick start Reference

22 crates binary FBX read + write lint rules VRC001–VRC062 M0–M5 green alpha · verify in Unity

New in the inspector: the in-browser Avatar inspector now opens your .fbx in a 3D viewer with skeleton and skin-weight overlays next to the humanoid rig check and performance rank. It runs the real Rust diagnose graph as WebAssembly — the file never leaves your machine.

The pipeline

Every tool sits at one point on the path from a raw export to a live avatar. Click a step to jump to its reference.

.fbx Inspect avatar fbx inspect Hierarchy, units, axes, blendshapes, unapplied transforms. .fbx Armature check / fix avatar armature fix Humanoid mapping, canonical renames, Blender repair script. Unity project Lint avatar lint SDK3 compliance across descriptor, params, menus, animators, clips. .fbx / project Stats avatar stats VRChat performance rank, PC and Android, offline. Unity YAML Generate / edit avatar toggle · anim-gen · asset set Clips, FX controllers, params, menus; surgical in-place edits; SDK2 → SDK3. VRCSDK Build & upload (you, in Unity) Not ours: interactive login, effectively Windows-only. live OSC avatar osc Send, capture, replay parameters; the analog-gesture daemon.

Preview sits alongside the whole chain: avatar render / avatar view draw the avatar, a world, or the avatar at the world's spawn without Unity. The full picture is on How it stacks.

What you can do today

Inspect in the browser

Drop an FBX: 3D viewer with skeleton and weight overlays, humanoid rig check, performance rank, blendshape inventory. WebAssembly, nothing uploaded.

analyzer.html

Fix the armature

Canonicalize a raw Mixamo rig so Unity auto-configures it as Humanoid; topology / scale / orientation issues flagged and emitted as a headless-Blender script.

avatar armature fix

Lint a project

SDK3 compliance over a whole Unity project: params, menus, descriptor refs, visemes, animator controllers, clip contents, PhysBones, Quest. Exits non-zero for CI.

avatar lint

Rank performance offline

VRChat's Excellent → Very Poor rank without Unity, against the PC and Android limit tables, including particles, constraints, and texture VRAM.

avatar stats

Generate assets

Emit .anim clips, blend trees, full FX controllers, expression params/menus — or a complete ten-file toggle bundle. Deterministic, diffable fileIDs.

avatar toggle · anim-gen

Edit Unity YAML safely

Change one value or swap one document in an existing asset by span-splicing the raw text: fileIDs, references, key order, and formatting all survive.

avatar asset set

Migrate SDK2 → SDK3

Retype the descriptor in place, convert DynamicBone → PhysBone by the SDK's own rules, rebuild FX from gesture overrides, get a VCC-openable project.

avatar migrate sdk3

Tune PhysBones

Inspect and retune a prefab's PhysBones in place: values, per-chain curves, split / stretch / flare / nudge chains, with render previews of the result.

avatar physbone

Preview without Unity

Headless GPU renders of the avatar, a world scene, or the avatar at the world's spawn, plus an interactive orbit / zoom / walk viewer.

avatar render · view

Drive avatars over OSC

Speak VRChat's OSC parameter protocol, capture and replay parameter streams against a controller, run the analog-gesture daemon on any hardware.

avatar osc

Hand it to an agent

--json and JSON Schemas across the read surface, and a non-writing MCP server exposing the diagnose and generate tools to any agent host.

avatar mcp serve

Browse the crates

Twenty-two crates from FBX I/O through migration and the runtime rig layer to the OSC daemon — purpose, key API, and status for each.

crates/

The two-layer model

Read this first. There are two file layers we own in Rust, and one step we don't.

1 3D asset · .fbx

Armature/skeleton, bone names, bind poses, skinning weights, blendshapes. Fully ours — native binary read and write via fbxcel.

2 Unity / VRChat · YAML

.anim, .controller, .asset, .prefab, scenes, .meta: descriptor, animator layers, menus/params. Read, lint, generate, and edit in place.

3 Upload · not ours

The VRCSDK control panel → VRChat servers. Interactive account login, effectively Windows-only. We hand off assets; you upload.

Where the build is

Status: early / alpha

The crates build green and are covered by tests (synthetic fixtures in CI, sample-gated real assets on the self-hosted runner), generated assets pass a headless Unity import-acceptance gate, and a real SDK2 avatar has been migrated, built, and uploaded to VRChat with these tools. Still: expect rough edges, verify in Unity before you rely on output, and treat APIs, CLI flags, and report formats as subject to change.

Milestone	Scope	Status
M0–M3	Workspace, armature diagnosis + repair, native FBX write-back, SDK3 lint	done
M4	Asset generation: clips, blend trees, FX controllers, params/menus, the toggle bundle	done
M5	OSC runtime + analog-gesture daemon	OpenXR input pending
alongside	Unity-YAML editing, SDK2 → SDK3 migration, PhysBone tuning, runtime rig, wgpu preview/viewer, MCP, the browser inspector	done

In flight: the daemon's on-device OpenXR input backend and OSCQuery browse/resolve discovery. The roadmap of record is PLAN.md; this site mirrors the committed docs under docs/.

cargo run -p avatar-cli -- --help