Free to start, with no payment details required. The free
tier includes 7 of the 16
templates with every result channel; paid plans unlock the full template catalog
and exports. Try it today.
Full-vehicle rig in bellcrank's 3D viewer — the Sample vehicle at rest Live: scroll to zoom once you've grabbed it; hover a hardpoint to read its coordinates.Interactive in a desktop browser. Shown here as a still of its opening view.
It solves your mechanism. It doesn't approximate it.
A constraint-based multibody kinematics and statics solver — the same class of formulation commercial MBS packages use.
Kinematics
Resolved at every step
Nothing is flattened to a sketch. A step with no solution fails loudly
instead of guessing.
Anti-geometry
From the solve, not the sweep
Anti-geometry and motion ratios come from the real mechanism, never
estimated.
Pinned to references
Checked against known answers
Roll center, instant centers, anti-geometry and statics — pinned
against published values and known formulas.
mcp
Describe the change. Your agent runs the rig.
bellcrank exposes a remote MCP server. Connect Claude Code, Cursor or any MCP client that can send an API key header, and your agent builds the axle, runs the sweep and reads roll center, camber gain and toe back. The agent writes the requests. The solver computes every channel it reads.
You: On "FS26 front", raise both upper-wishbone
inner pivots by 5 mm. Compare roll center height, camber gain and bump steer
over ±50 mm of heave, before and after.
Agent: Roll center
height, camber gain and bump steer (toe against wheel travel), for both revisions,
side by side.
Illustrative session. Tool names and argument shapes match the live server.
Ids are shortened, and no results are shown.
Build
Hardpoints
The agent picks a topology from the catalog, builds the axle and the
motion, and patches hardpoints. With a checksum guard, a concurrent
edit is refused instead of overwritten.
Solve
The solver's numbers, not the model's
Every run goes to the same solver through the same /v1 API the app uses. Roll center, camber gain and toe gain come from its
post-processor, never from the language model.
Read
Only the curves you asked for
A result arrives as a compact summary with up to three sampled steps
per channel. The agent then pulls full values only for the channels
and steps it names.
One contract
Nothing new to trust
A key carries the same scope, rate limit, credit pool and plan through
MCP as over REST. Every plan can mint one.
the incumbents
Most suspension software belongs in a museum.
The tools the industry still designs suspension with are desktop software from another era — installed per machine, licensed per seat, barely changed in decades. Your car deserves software from this decade.
Exhibit 001
Desktop suspension software
c. 1985–2012 · compiled for one OS · licensed per install
Once the state of the art. Installed from a CD, tied to a dongle,
exported to spreadsheet. Typically found on a single laptop in the shop
— the one nobody is allowed to update.
Donated by teams that moved to the browser.
explore
Look closer before you sign up.
Three closer looks: the topology catalog with plan badges, two front suspensions compared over one sweep, and a solved 1 g load case.
Joint reactions, per-body loads and steering torque, solved for a 1 g
corner and drawn in 3D — the add-on module desktop tools charge extra
for.
revisions
Every save is a revision.
Axles, vehicles, motions and load cases carry a git-style, append-only history — checksummed, authored, automatic. No "final_v3_FINAL" files, no versioning ceremony.
History
Browse and restore
Every design change appends an immutable revision — number, checksum,
author, timestamp. Load any revision back into the editor and save it
to restore; the chain is never rewritten.
Provenance
Results remember their inputs
Every new run records the revision checksum of the assembly and the
motion or load case that produced it — so you know which geometry made
which curve.
teams
One garage for the whole team.
Create a team and switch into its shared space: every axle, vehicle, motion, load case, result and workspace in one place — with revision history naming the teammate behind every change.
Shared space
Everything, together
Flip between personal and team context from the sidebar's team
switcher. In team mode every asset type is the team's shared copy —
created, edited and simulated by any member.
Invites & seats
E-mail or link, your call
Invite by e-mail or share a copyable invite link. Invitations reserve
a seat and are bound to the invited address; owners manage seats,
revoke invites and transfer ownership.
Student teams
Built for FSAE squads
A dedicated student team type: three seats on a shared university
e-mail domain, verified by us. Formula Student and Baja teams run the
same solver the pros do.
pricing
Simple plans. The free tier is permanent.
Start free with no payment details. The free tier is permanent; paid plans unlock the full template catalog and exports.
Free
€ 0 /mo
Permanent — not a countdown
credits
5/mo
saves
10/mo
templates
7
outputs
absolute
points
bodies
difference
positional derivatives
Double wishbone, five-link and MacPherson, both rigs
Create an account, model a suspension from your own hardpoints, and run it on the rig. No download, no license, no payment details — and the free tier is permanent.
