Quilter vs Flux: Two Different Answers to AI PCB Layout

Quilter takes a finished schematic, Flux starts from a blank project

Quilter's documentation asks for two things: a schematic and a "starter" board file that already has a valid board outline, netlist and component footprints. Parts you want Quilter to place sit outside the outline. You then describe the stackup, fabricator, layer count and tolerances in a separate step, Quilter generates layout candidates, and you download the one you pick back into your original CAD format for review. The tools its site lists are Altium Designer, Cadence, OrCAD, Siemens Xpedition and KiCad.

Quilter is explicit about scope. Its free-tier page says "Quilter is not an AI schematic generator," and the product does nothing upstream of a captured design. If the circuit is not drawn yet, Quilter has nothing to work on.

Flux covers the whole flow in one browser workspace. Its FAQ describes the AI as drafting schematics, researching parts and routing traces, with everything editable in the browser and real-time collaboration built in. For fabrication it exports Gerbers, drill files, a BoM, pick-and-place and standard netlists.

What "AI layout" means in each tool

Quilter treats placement and routing as one problem, says its engine is trained with reinforcement learning against physics, and shows the physics checks it ran on each candidate. The output is not one board but many candidates, and an engineer reviews them, adjusts the chosen one and sends it to fab. That review step is part of the workflow, not an afterthought.

Quilter also publishes what its engine handles today: 100 to 1,000 components per board, strongest performance at roughly 2,000 to 5,000 pins to route, pin density under 20%, and through-hole vias. Blind and buried vias are in development, BGA fanout is in beta, length matching is listed as coming soon, and for RF it suggests pre-routing those nets yourself. A memory interface that needs length-matched lanes is outside what it lists as live.

In Flux, routing is one of the things the AI agent does inside the same project as the schematic, and you edit the result directly in the browser. That keeps the loop short, but the layout lives in Flux. Its FAQ says layout import is not supported yet: Altium (ASCII) and Cadence (EDIF) schematics and KiCad part libraries come across, an existing board does not.

Pricing and data terms, read from both vendors

Flux has no free plan. Each individual plan starts with a 14-day trial, and the pricing page lists Explore at $40/mo billed annually ($50 month to month) with 40 AI compute units (ACUs) a month, Build at $80/mo annually ($100 monthly) with 120 ACUs, and Pro at $200/mo annually ($250 monthly) with 400 ACUs. Teams is $120 per editor per month billed annually, and extra AI usage on Build and Pro is $2 per ACU. After the trial, the FAQ says your account still works for public projects, but editing private projects, exporting and using AI need a paid plan.

Quilter's free tier covers academic, personal and eligible professional exploratory R&D, and its comparison table lists business-size eligibility as "less than 10 people, less than $50K revenue." The same table says the free tier uses your board's metadata (outline, footprints, constraints) and/or input files to generate training puzzles for its engine, while Enterprise designs are never used for training. Paid pricing is not published as a list: Quilter prices each board by the number of unrouted pins at upload, with cloud or self-hosted deployment.

For a company over either eligibility line, or anyone whose customer contract rules out training use, the free tier is off the table and the conversation goes to Quilter's sales team.

Can you use Quilter and Flux together?

Not through any path either vendor documents. Quilter's list of supported formats does not include Flux, and Flux's FAQ describes manufacturing outputs and netlists rather than an Altium or KiCad project export. A netlist alone is not what Quilter asks for, since it wants a starter board file with an outline and footprints.

So in practice this is a choice of workflow. If your team already works in Altium, Cadence or KiCad and layout time is the bottleneck, Quilter adds to what you have. If you want one browser tool from idea to Gerbers and a subscription is fine, Flux replaces the stack.

A third path: ProtoFlow

ProtoFlow is a free desktop PCB design app for Windows, macOS and Linux, and the design files stay on your machine. The AI drafts an editable schematic with real parts from a plain-English prompt, the Copilot works inside the editor, and part search covers LCSC, DigiKey and Mouser with symbol and footprint together. From there you sync to layout, set the stackup, run the auto-router, pour copper, run DRC and export Gerber X2, Excellon drills, BOM and CPL files for JLCPCB assembly.

ProtoFlow's auto-router runs inside the same desktop editor, driven by presets and layer filters, with DRC right after it, so the whole board stays in one tool and on your machine instead of moving between a browser workspace and an upload service.

Because ProtoFlow exports KiCad and Altium projects, both formats Quilter lists, the two can sit in one flow: capture in ProtoFlow, export the KiCad project, and send the layout job to Quilter when the board justifies it. Open the export in KiCad first to confirm the outline, netlist and footprints came through.