TL;DR: No single free online circuit simulator is best at everything in 2026 — CircuitVerse for open-source digital logic, DigiSim free tier for curriculum and CPU components, Tinkercad for Arduino and breadboard, Falstad for analog. Logisim Evolution is free and excellent but desktop-only, not online.
If you’re searching for a free online circuit simulator in 2026, the good news is there are several strong options. The bad news is they’re each strong at different things, and “free” means slightly different things for each (free forever vs free tier, account required vs not, paywalled features vs not). This post compares the four serious online options honestly, so you can pick the right one for your specific use case.
We are the team behind DigiSim.io and we’ll be transparent about where DigiSim’s free tier is generous, where it’s paywalled, and where another tool is plainly the better free choice.
What “Free Online” Actually Means in 2026
Before the comparisons, four definitions worth being precise about:
- Free forever — the entire product, no paywalls, no premium tiers. CircuitVerse, Falstad, and Tinkercad’s individual offering fit here.
- Free tier — a generous slice is free, with paid tiers for advanced features. DigiSim.io fits here.
- Free, account required — you can use it for free but you need to register. Tinkercad (Autodesk login).
- Free, no account needed — open the URL and go. Falstad fits here. DigiSim’s free tier lets you try without an account but saves require one.
We’ll flag which definition applies in each section.
Master Comparison Table — Free Online Simulators
| Tool | Free model | Account | Save circuits | Digital logic depth | Analog | Arduino | Animated lessons |
|---|---|---|---|---|---|---|---|
| DigiSim.io free tier | Free tier (paid upgrades) | Optional to try | Limited free saves | Deep (incl. CPU) | No | No | Yes (SimCast) |
| CircuitVerse | Free forever | Yes | Unlimited | Deep | No | No | Some |
| Tinkercad Circuits | Free forever | Required (Autodesk) | Unlimited | Limited | Yes | Yes | Project tutorials |
| Falstad | Free forever | No | Export as text | Limited | Strong | No | No |
| Logisim Evolution | Free forever (desktop) | No | Yes (.circ files) | Deep | No | No | No |
A note on Logisim Evolution: it is a desktop Java app, not online. We’ve included it in the table so you know what you’d be giving up by going browser-only, but the rest of this post is about online tools specifically. If a Java desktop install is acceptable, see our DigiSim vs Logisim Evolution comparison.
1. DigiSim.io Free Tier — Best Free Curriculum
DigiSim.io has a free tier that’s tuned for learners working through digital logic fundamentals. You get access to the simulator, a meaningful subset of the 70+ components (including the basics through flip-flops and counters), and the ability to try the SimCast lesson system in seven languages.
What’s free
- Browser-based simulator, no install
- Core component library (gates, flip-flops, MUX/DEMUX, counters, etc.)
- Try-before-account: you can build circuits in the free sandbox without signing up
- Animated SimCast lessons — a meaningful slice of the curriculum
- Multilingual UI (en, zh, ja, es, ko, de, fr)
- Public templates browseable and runnable
What’s paywalled
- Unlimited cloud saves
- The deeper template library (CPU primitives, complex multi-stage circuits)
- Some advanced lesson content
- Power-user features
Best for: Self-learners, students working through introductory digital logic, anyone who wants curriculum and tool in one place. If you’re working from gates up to flip-flops, the free tier covers a real chunk of the journey. Once you reach CPU architecture, the paid tier becomes worth considering.
Honest caveat: If “completely free, no paywall ever” is your hard constraint, DigiSim free tier won’t satisfy it. CircuitVerse will.
Try it: Basic Switch and Light Demo and Digital Logic 101.
2. CircuitVerse — Best Free Forever for Digital Logic
CircuitVerse is open source, browser-based, and free forever for individuals. It is, in our opinion, the strongest “free forever” online digital logic simulator in 2026.
What’s free
- Entire simulator
- Comprehensive digital logic component library
- Save circuits to the cloud, unlimited
- Public gallery of community-contributed circuits
- Classroom assignment workflow
What’s paywalled
- Nothing for individuals. School plans exist for institutional features but the core product is free.
Best for: Hobbyists, students whose institutions require open-source tooling, anyone who wants a free-forever browser-based simulator with no asterisks. The community gallery and “Circuit of the Day” feature make it especially good for self-learners who like to browse and remix.
Honest caveat: Lessons content is lighter than DigiSim’s, and CPU primitives aren’t as turn-key — you build them from gate-level rather than dropping in a prebuilt control unit. For pure simulator capability, though, it’s excellent.
Site: circuitverse.org.
3. Tinkercad Circuits — Best Free for Arduino and Breadboard
Tinkercad Circuits by Autodesk is free for individuals and is the standard recommendation for Arduino, breadboard, and analog/mixed-signal work in the browser.
What’s free
- Entire simulator
- Arduino IDE integration (write, upload, run code)
- Realistic breadboard view
- Analog components (resistors, capacitors, sensors, motors, LEDs)
- Save circuits to the cloud, unlimited
- Project-style tutorials
What’s paywalled
- Nothing for individual use. Educator features have separate tiers but the core product is free.
What’s required
- An Autodesk account. This is the friction point — some classrooms (especially K-12 with parental consent overhead) find this a meaningful barrier.
Best for: Arduino learners, makerspaces, freshman intro electronics, anyone working with physical-style breadboarding and analog components.
Honest caveat: Pure digital logic depth is limited. There are basic gates, but no CPU primitives, no curated digital-logic curriculum, and the abstractions are physical-component-first rather than schematic-first. If you’re learning digital logic specifically, this isn’t the right tool. See our DigiSim vs Tinkercad Circuits comparison for the full breakdown.
Site: tinkercad.com/circuits.
4. Falstad Circuit Simulator — Best Free for Analog
Paul Falstad’s circuit simulator is the longest-running free online simulator we know. Originally a Java applet, now JavaScript. It’s exceptional at analog and transistor-level simulation, and it has the friction-free model of “open the URL, click play.”
What’s free
- Entire simulator
- Strong analog simulation (op-amps, RC circuits, transistors)
- A huge library of pre-built example circuits
- No account, no login, no telemetry
- Source available
What’s paywalled
- Nothing.
Best for: Analog electronics, transistor-level work, op-amp study, anyone who values “no friction ever” above curated curriculum.
Honest caveat: Less curated digital-logic library, no save-to-cloud (circuits export as text strings you copy-paste), no animated lessons, mostly English-first UI. For curated digital logic teaching, this isn’t the tool. For analog, it’s wonderful.
Site: falstad.com/circuit.
What’s Free, In More Detail
| Capability | DigiSim free | CircuitVerse | Tinkercad | Falstad |
|---|---|---|---|---|
| Basic gates (AND, OR, NOT, etc.) | Yes | Yes | Yes | Yes |
| XOR, XNOR, NAND, NOR | Yes | Yes | Yes | Yes |
| SR / D / JK latches and flip-flops | Yes | Yes | Limited | Yes |
| Multiplexers / decoders | Yes | Yes | Limited | Yes |
| Counters | Yes | Yes | Limited | Limited |
| Full ALU | Free template tier varies | Build-your-own | No | No |
| RAM / ROM | Limited (free tier) | Yes | No | Limited |
| CPU primitives (PC, IR, control unit) | Paywalled | Build-your-own | No | No |
| Arduino code | No | No | Yes | No |
| Breadboard view | No | No | Yes | No |
| Analog components | No | No | Yes | Yes (deep) |
| Animated step-by-step lessons | Yes (some free) | Some lessons | Project tutorials | No |
| Multilingual UI | Yes (7 languages) | Some | Some | English-first |
| Save to cloud | Limited free tier | Unlimited | Unlimited | Export as text |
| Embed in webpage | Yes | Yes | Limited | Limited |
| Account required | Optional to try | Yes | Yes | No |
Recommendation Matrix — Pick by Use Case
| Use case | Our pick (free) | Notes |
|---|---|---|
| Students learning gates and basic combinational logic | DigiSim free tier | SimCast lessons accelerate understanding; CircuitVerse a great alternative |
| Students learning sequential logic (latches, flip-flops, counters) | DigiSim free tier | Animated propagation + oscilloscope helps a lot |
| Arduino beginners | Tinkercad | The clear winner; nothing else does Arduino as well |
| Breadboard / physical wiring practice | Tinkercad | Realistic breadboard view |
| Analog / op-amp / transistor study | Falstad | Best free analog tool online |
| CPU architecture from scratch | DigiSim (likely paid tier) | Free tier introduces concepts; CPU primitives are paywalled |
| Open-source classroom adoption | CircuitVerse | Free forever, GPL/MIT-style licensing |
| Multilingual classroom (zh/ja/es/ko/de/fr) | DigiSim free tier | 7 languages of UI and lessons |
| Embedding circuits in a blog or LMS | DigiSim free tier or CircuitVerse | Both support iframe embed |
| Privacy-strict environment (no accounts) | Falstad | No login at all |
| Research / quick prototyping | Falstad for analog, CircuitVerse for digital | No friction |
| K-12 classroom with parental consent overhead | DigiSim free tier | Try-before-account model reduces consent friction |
| Self-learner with no electronics background | Tinkercad then DigiSim | Tinkercad to get comfortable, DigiSim once you focus on logic |
On DigiSim’s Free Tier — A Direct Note
Three things we want to be honest about regarding DigiSim’s free tier:
It’s genuinely useful for fundamentals. You can spend weeks in the free tier learning gates, flip-flops, counters, and basic combinational logic without hitting a paywall. We mean that.
It’s paywalled at depth. When you reach CPU architecture, the program counter, the control unit, the deeper templates — that’s where the paid tier kicks in. We chose one-time purchase, no subscription, because we think students shouldn’t pay rent on a learning tool — but it is still not free.
For “free forever, no paywall ever” use cases, CircuitVerse is the better fit. We say this without grudge. Different products optimize for different things.
On Hidden Costs
A note on costs that aren’t dollar-priced:
- Account friction — Tinkercad’s required Autodesk login costs time and (for K-12) parental consent.
- Privacy — All cloud-backed tools (DigiSim, CircuitVerse, Tinkercad) involve some data going to servers. Falstad and Logisim Evolution don’t.
- Lock-in — File formats are not interchangeable. Building a deep portfolio in one tool is hard to migrate.
- Learning curve — Tinkercad’s onboarding is the smoothest; Falstad’s is the steepest for digital-only users.
- Ad load — None of these tools serve ads in any meaningful way as of 2026, which is worth appreciating.
What About Logisim Evolution?
It’s free, it’s open source, it’s excellent — but it’s a Java desktop app, not an online simulator. If a desktop install is acceptable, it’s a strong choice for digital logic. Read our DigiSim vs Logisim Evolution comparison for the full picture. For this post we excluded it because the question was specifically online.
The same applies to Digital (hneemann) — open source, desktop, strong digital logic, and adds VHDL/Verilog export. Mentioned for completeness; not online.
A Suggested Path for Free Self-Learners
If you have zero budget and want to learn digital logic from scratch online, here’s a path that uses each tool’s free strengths:
- Start in DigiSim free tier — work through Digital Logic 101 and the logic gate truth tables guide. Open the basic switch and light demo and the full adder template.
- Move to flip-flops — read the D flip-flop deep dive and try the edge-triggered D flip-flop template.
- Add CircuitVerse to your toolbox — explore the community gallery. Different circuits, different idioms; useful exposure.
- For Arduino projects, switch to Tinkercad. It’s the right tool.
- For analog or transistor questions, Falstad. Same logic.
- When you hit CPU architecture and need primitives, decide: pay for DigiSim’s tier (one-time, no subscription), or build from primitives in CircuitVerse. Both work; one is faster.
The Bottom Line
There is no single best free online circuit simulator in 2026 — there are excellent free options for each use case:
- Pure digital logic with curriculum: DigiSim free tier is generous and the lessons are excellent
- Pure digital logic, free forever: CircuitVerse
- Arduino and breadboard: Tinkercad
- Analog and transistor work: Falstad
Pick the one that fits what you’re trying to do today, and don’t be afraid to use multiple tools across a learning journey. They’re free; the cost of switching is your time, not your wallet.
Frequently Asked Questions
“Is there a truly free online digital logic simulator that includes CPU components?”
Closest answer: CircuitVerse, where you build CPU components from primitives. DigiSim’s free tier exposes some CPU concepts but the deeper templates are paywalled. If “free + turn-key CPU primitives” is the requirement, you’d want Logisim Evolution or Digital — both desktop, both free.
“Can I use Falstad for digital logic teaching?”
You can, and a few instructors do. The digital library is functional but less curated than CircuitVerse’s or DigiSim’s, and it lacks the curriculum-shaped lessons. For occasional digital reference inside an analog-heavy course, fine. For a digital-logic-as-subject course, we’d pick CircuitVerse or DigiSim instead.
“Is Tinkercad free for teachers?”
Yes, Tinkercad is free for individual use including teachers. There are educator-specific features for classroom management; check Autodesk’s current educator program for specifics. The required Autodesk login is the only meaningful friction.
“What about Multisim Live?”
Multisim Live is browser-based and has a free tier, with paid tiers for advanced features. We didn’t include it in the main comparison because its strength is analog/SPICE simulation, similar to Falstad — and Falstad’s no-account, no-login model wins that head-to-head for free use cases.
“Can students collaborate in real-time on these tools?”
As of 2026, real-time multi-user collaboration on a single circuit isn’t a strong suit of any of these tools. Sharing via URL or file is the standard model. CircuitVerse and DigiSim both support iframe embedding which can enable some collaborative scenarios.
Caveats and Things That Change
A short list of things that shift over time and may change after this post:
- Pricing models. Tools occasionally introduce new tiers or change free-tier limits. Always check the current pricing before committing a class.
- Account requirements. Tinkercad’s Autodesk-login model and DigiSim’s free-tier-trial-without-account are current as of 2026, but vendor decisions can change.
- Feature parity. The free options here are all under active development. CircuitVerse adds features regularly; we ship aggressively at DigiSim. The gap on any single feature today may not be the gap next semester.
- Open-source status. Open source is hard to undo, so CircuitVerse, Logisim Evolution, and Digital are stable on this dimension. Closed-source tools’ availability depends on the vendor.
When we update this post — and we will — we’ll change the updatedAt date in the frontmatter. If you’re reading it more than a few months after that date, sanity-check current pricing and feature claims with the tools’ own websites.
Try DigiSim’s Free Tier
If digital logic is your destination, the fastest way to evaluate DigiSim is to spend ten minutes in the free tier. Open Your first 5 minutes with DigiSim.io for a guided start, or jump straight to the SR latch demonstration and watch the SimCast walkthrough. From there, the digital logic roadmap charts the path through the rest of the curriculum.
