Flux (flux.ai) and KiCad approach PCB design from opposite directions. Flux is a modern, browser-based tool built around real-time collaboration and an AI copilot. KiCad is a mature, free, open-source desktop suite that runs entirely on your own machine. Both design real boards — the question is which set of tradeoffs fits how you work.
Short answer: If you value real-time, Google-Docs-style collaboration, an AI co-designer, and a zero-install start, Flux is genuinely pleasant — especially for teams and quick prototypes. If you value owning your files outright, working offline, paying nothing, and a deep, proven toolchain, KiCad is hard to beat. The deciding factor is usually cloud convenience versus local ownership, not raw drawing ability.
What Flux is
Flux is a full ECAD tool that runs in a web browser — no install, no license server. It leans into three ideas that traditional desktop EDA doesn't do natively:
- Real-time collaboration. Sharing a design is as simple as sharing a link. Multiple people can co-edit live, leave inline comments right on the schematic or board, and see each other's changes — much like Google Docs.
- AI Copilot. Flux's AI co-designer can help wire up a schematic, suggest parts based on IC datasheets (bypass caps, pull-ups/pull-downs), run design reviews that catch things like missing decoupling capacitors, and answer questions in context.
- A shared, community library. Instead of everyone maintaining their own symbols and footprints, Flux offers a single, continuously updated library of vetted community parts.
These are real strengths. For a distributed team, or for getting a first prototype moving fast, that low barrier to entry is the whole pitch — and it delivers.
Cost and licensing
This is where the models diverge sharply.
KiCad is released under the GNU GPL. It is free for any use — commercial hardware included — with no seat count, no feature tiers, and no subscription. The boards you design are yours to manufacture and sell.
Flux has a free tier, but it is oriented toward viewing and interacting with public community projects. Editing private projects, exporting, and using the AI features generally require a paid plan. Paid tiers are subscription-based and priced per editor, and AI usage is metered separately through compute credits that replenish monthly (and cost extra beyond your allowance). Flux also offers a time-limited trial of premium features.
| Flux | KiCad | |
|---|---|---|
| License | Proprietary, subscription | Free / open source (GPL) |
| Free tier | Yes, but mostly public projects; private work + AI + export need a paid plan | Fully free, no limits |
| Paid pricing | Per-editor subscription + metered AI credits | None |
| Commercial use | Paid plan | Free |
Exact prices and tier names change, so check Flux's pricing page before committing. The structural point is stable: serious Flux work is a recurring cost; KiCad is not.
Cloud vs local: data ownership and offline
Flux runs in the cloud. Your designs live on Flux's servers, which is exactly what makes the real-time collaboration work — and exactly what some engineers hesitate over. It means you need an internet connection to design, and your project data sits on a third party's infrastructure under their terms. KiCad users on forums repeatedly raise portability and export as concerns with cloud-centralized tools.
KiCad is the opposite. It's a desktop application that runs locally and fully offline. Your files are plain-text .kicad_sch and .kicad_pcb on your own disk — you own them, you back them up, you move them anywhere, and nothing stops working if a subscription lapses or a service goes away.
| Flux | KiCad | |
|---|---|---|
| Where it runs | Browser, cloud-hosted | Local desktop app |
| Offline use | Needs internet | Fully offline |
| Where files live | Flux's servers | Your machine |
| Data ownership | Governed by their service | Entirely yours |
| Platform | Anything with a browser | Windows, macOS, Linux |
If your work is sensitive, export-controlled, or simply must not depend on a vendor staying in business, local-and-yours is a hard requirement — and that's KiCad.
PCB capability and maturity
Both tools draw real boards. Flux handles multi-layer designs and is evolving fast, with the AI copilot removing a lot of the tedium for common circuits. But it's a younger tool, and for deep or unusual designs it's less battle-tested.
KiCad has years of production hardware behind it: a mature schematic editor, a push-and-shove router with length and delay tuning, a stackup editor and impedance calculator, 3D/STEP export, and support for up to 32 copper layers. Its community is enormous, which means answers, tutorials, and example projects for nearly anything you hit. For complex, high-layer-count, or long-lived designs, that maturity matters. If you're weighing whether an open-source tool is truly ready for serious work, we dug into exactly that question.
The collaboration and AI angle — fairly
It's worth being honest: this is where Flux is ahead, and it's not a gimmick. KiCad has no built-in multiplayer editing and no AI co-designer. If your team wants several engineers in the same board at once with live comments, Flux does that natively today; KiCad doesn't.
The counterpoint is that KiCad's plain-text files make it a natural fit for Git, which gives you history, diffs, branches, and reproducible releases — the traceability serious hardware teams actually need. It's asynchronous rather than live, but it's rock-solid and vendor-independent. (We wrote a full guide to KiCad with Git version control.) So the real tradeoff is live cloud collaboration versus durable, owned, versioned history — different strengths for different teams, not a knockout either way.
When to choose which
Choose Flux if: you want zero-install onboarding, live multiplayer editing with a shared library, and an AI copilot to accelerate routine design — and you're comfortable with a cloud tool, a subscription for real use, and your data living on their servers.
Choose KiCad if: you want a free, fully-owned toolchain that runs offline, keeps your files on your own disk, and has the depth and community to carry complex boards for years. If you're comparing free options broadly, our best free PCB design software roundup puts KiCad in context.
The honest conclusion
Flux is a genuinely modern take on EDA — browser-based, collaborative, AI-assisted, and easy to start. Those are real advantages, especially for teams and fast prototypes. What you trade for them is ownership: cloud hosting, internet dependence, and a subscription for anything beyond the basics. KiCad trades the polish of live collaboration for something many engineers won't give up — free, local, offline, and files that are unambiguously yours.
If you land on KiCad, the one thing it doesn't hand you out of the box is an automated output workflow. That's what GoForFab adds: connect a KiCad project and every push regenerates the full manufacturing package — Gerbers, BOM, CPL, DRC/ERC reports, 3D renders — automatically, so your outputs are always current and reproducible. It's free forever for the core workflow, works with your existing KiCad files, and keeps everything you own local while giving you the automated pipeline that cloud tools promise.
Sources: Flux pricing, Flux vs. KiCad (flux.ai), Electronics-Lab: Flux.ai review, KiCad forum: anybody used Flux.ai?