Free Online Circuit Simulators Compared (2026)

TL;DR: Start with the subject, not the price tag. CircuitVerse is the strongest candidate for a free, open-source digital-logic classroom; DigiSim’s free tier combines a 16-component Logic core with browser-local saving and guided lessons; Tinkercad Circuits serves Arduino and virtual-breadboard activities; and Falstad/CircuitJS1 is excellent for immediate, account-free electronic-circuit exploration. Logisim Evolution and Digital are also free, but they are desktop applications rather than online tools.

“Free online circuit simulator” covers products with very different models. One may be an open-source logic editor, another a proprietary free tier, another an Arduino breadboard, and another an electronic-circuit visualizer. Comparing them by component-count checkboxes alone produces a misleading answer.

This guide separates four questions:

1. What can a learner use without paying?
2. Is an account required to build, save, or submit work?
3. Can work be exported or recovered outside the hosted account?
4. Does the simulator model the kind of circuit the course actually teaches?

Disclosure and verification: DigiSim publishes this article and is one of the products compared. We checked the claims on July 27, 2026 against official product pages, documentation, and source repositories. We did not conduct a controlled usability or numerical-accuracy benchmark, and no competing vendor paid for inclusion. Features and hosted-service terms can change, so verify a finalist before assigning it to a class.

Product-fact freshness: DigiSim product, access, and route facts were reviewed against the August 31, 2026 audited source snapshot and aligned on September 1, 2026. Third-party facts retain the July 27 review date above and should be rechecked before adoption.

What “Free” Means Here

The useful distinctions are more precise than “free forever”:

• Free software: the source is available under a license that permits continued use, study, and modification. CircuitVerse and CircuitJS1 meet this definition; their hosted services are separate operational concerns.
• Free hosted service: the vendor or project currently offers browser access without charging. That is current behavior, not a guarantee that hosting terms can never change.
• Free tier: part of a commercial product is available at no cost, with documented paid limits or features. DigiSim uses this model.
• Account-free use: a learner can open the editor and work without registering. This reduces onboarding friction, but it does not by itself establish privacy, offline support, or data portability.

Comparison at a Glance

The table intentionally does not label one product “best.” Each one is strongest in a different course.

1. DigiSim Free — Guided Digital-Logic Fundamentals

DigiSim combines a browser logic editor with templates and narrated SimCast lessons. The current Free policy exposes 16 of 61 Logic components and saves circuits locally in the browser.

Included at no cost

• The browser-based digital-logic sandbox, with 16 of 61 components
• Browser-local saving without requiring a cloud account
• Free .digi project-file export
• With a Free account, 5 Logic cloud saves and 2 unlisted links that expire after 14 days
• Community templates and selected learning content
• A localized interface across seven languages
• Live circuit embeds on supported webpages

Paid boundary

Pro and the Founder offer, while available, add the complete component and lesson catalogs, CPU-side components, and expanded cloud and unlisted-link quotas. Classroom is a separately confirmed institutional preview, not a default checkout plan. Features still vary by lab, so current access belongs on the live pricing page, not in a purchasing decision copied from an old article.

Where it fits

DigiSim Free is useful when a beginner needs an explanation alongside the canvas. A learner can read Digital Logic 101, inspect a basic switch and light, and then work through truth tables and sequential logic without installing software.

Important limits

Browser-local storage is convenient, but it is not an institutional backup: clearing site data, changing browsers, or moving devices can remove it. The free plan’s component cap also makes it unsuitable for some larger assignments. DigiSim is proprietary, so it does not satisfy an open-source or self-hosting policy.

2. CircuitVerse — Open-Source Digital Logic in the Browser

CircuitVerse is a browser logic simulator with an MIT-licensed codebase. Its official documentation describes both online and local circuit saving, multibit wires, subcircuits, system-level components, timing diagrams, delay controls, image export, project URLs, collaboration, forks, and iframe embeds.

For educators, the distinction is even clearer: CircuitVerse provides groups, mentors, assignments, deadlines, element restrictions, grades, remarks, and CSV grade export. Its testbench workflow lets an author express input cases and expected outputs instead of grading every circuit only by manual inspection.

Where it fits

• Institutions that require an open-source browser tool
• Courses that need group, assignment, and grading workflows
• Assignments that benefit from testbenches or timing diagrams
• Instructors who want public projects, forks, downloadable files, or live embeds
• Organizations prepared to self-host if operational control is worth the maintenance cost

Important limits

An open-source license does not make the hosted service offline or maintenance-free. Accounts are part of the hosted dashboard and classroom workflow, and self-hosting transfers security updates, backups, availability, email delivery, and user support to the institution.

CircuitVerse also does not package the same kind of narrated, sequenced curriculum as DigiSim. That is irrelevant when an instructor already has strong course materials, but important for an unsupported self-learner.

3. Tinkercad Circuits — Arduino and Breadboard Learning

Tinkercad Circuits is Autodesk’s free browser environment for virtual breadboards, electronic components, and programmable boards. Autodesk currently presents it as a way to simulate and program Arduino and breadboard components, with guided starter activities.

Where it fits

• First Arduino programs connected to LEDs, buttons, and sensors
• Breadboard-layout practice before a physical lab
• Maker activities that combine code and circuit wiring
• Introductory electronics demonstrations using familiar physical-looking parts

Important limits

Tinkercad is not organized as a gate-to-register-to-CPU curriculum. A virtual breadboard result also cannot establish that a physical circuit will tolerate real supply variation, noise, loading, part tolerances, or wiring faults.

Its project workflow depends on an Autodesk account and hosted service. Before using it with minors or institutional data, educators should review the current account, privacy, and data-retention requirements rather than assuming “free” answers those questions.

4. Falstad / CircuitJS1 — Frictionless Electronic Exploration

Falstad’s Circuit Simulator is a hosted build of CircuitJS1, an open-source electronic-circuit simulator that runs in the browser. It opens directly into an interactive example, animates voltage and current behavior, and includes a broad example menu.

Where it fits

• Quick RC, filter, oscillator, transistor, and op-amp exploration
• Demonstrating how an electronic circuit changes over time
• Account-free experimentation
• Courses that want import/export, encoded links, or iframe examples
• Users who want the option to inspect or self-host the GPL-licensed source

Important limits

Falstad includes digital elements, but it is not a digital-logic course-management platform. It has neither CircuitVerse’s assignments and grading nor DigiSim’s narrated curriculum. Its animated model is excellent for intuition, but any result used for engineering decisions must be checked against the required model, analysis tool, and physical measurements.

Capability Map

“Yes” means the official product documents the capability; it does not mean equivalent depth or accuracy across products.

A Better Selection Test

Instead of trying four editors at random, choose two finalists and run the same small pilot:

1. Onboarding: ask a new learner to open the tool and build a half adder.
2. Sequential behavior: build or load a counter and inspect several clock cycles.
3. Verification: test normal cases and at least one deliberately incorrect circuit.
4. Recovery: close the browser, reopen the project, export it if possible, and restore it on another machine.
5. Teaching workflow: distribute an assignment, collect a submission, leave feedback, and export a grade.
6. Accessibility: complete the core workflow with keyboard navigation, zoom, and the assistive technology relevant to the class.
7. Embedding: test the actual LMS or website. Content Security Policy, administrator settings, cookie restrictions, and iframe rules can block an embed even when the simulator supports one.

Measure setup time, failure points, grading time, and recovery—not which homepage has the longest checklist.

Recommendations by Use Case

For a zero-budget digital-logic course, CircuitVerse deserves the first pilot because its source, hosted simulator, classroom workflow, and testing tools are all documented. For a self-learner who needs the teaching material as much as the editor, DigiSim Free is a sensible comparison despite its cap. Those conclusions can both be true.

Hidden Costs That Still Matter

No-dollar software can carry other costs:

• Accounts and consent: registration, student identity, and parental or institutional approval
• Course conversion: rebuilding circuits, screenshots, instructions, answer keys, and rubrics
• Support: training students and troubleshooting browsers, Java, or managed devices
• Data recovery: exporting work, backing it up, and retaining it after a student leaves
• Accessibility: remediating a workflow that does not meet the class’s needs
• Service dependency: accepting changes to a hosted product, authentication system, or pricing model
• Self-hosting: applying patches, monitoring uptime, sending email, protecting data, and supporting users

Open source improves control and exit options; it does not eliminate operating cost. A commercial service can reduce administration; it does not eliminate vendor dependency.

What About Logisim Evolution and Digital?

Logisim Evolution and Digital are free, open-source desktop applications. They are excluded from the main table only because this article is about online tools.

Both are serious candidates when offline operation is required. Logisim Evolution documents chronograms, VHDL components, and FPGA-board integration. Digital documents circuit tests, analysis and synthesis tools, FSM support, HDL integration/export, and FPGA workflows. Their tradeoff is desktop deployment rather than a hosted browser classroom.

Frequently Asked Questions

Is CircuitVerse “free forever”?

Its project currently describes the hosted simulator as free, and its source is available under the MIT license. The license gives users durable rights to the code; it cannot guarantee that a particular organization will host a particular service forever. Preserve local circuit files and assess self-hosting only if your institution can operate it.

Can I use Falstad for digital logic?

Yes. It includes digital components and can be valuable in an electronics course. For a course whose central work is Boolean design, hierarchical digital systems, testbenches, assignments, and grading, a dedicated logic platform is generally a closer fit.

Is Tinkercad a replacement for a physical electronics lab?

No simulator reproduces every physical failure mode. Tinkercad is useful for preparation and iteration; hardware remains necessary when the outcome includes instrument use, component handling, wiring discipline, tolerance, noise, power, or fault diagnosis.

Can these simulators be embedded in an LMS?

DigiSim, CircuitVerse, and CircuitJS1 document iframe workflows. The target LMS must also permit the frame and its origin. Test authentication, cookies, mobile layout, keyboard access, and submission behavior in the institution’s real configuration.

Which tool can students use without an account?

Falstad’s public editor is directly usable without registration. DigiSim permits local free work without an account. CircuitVerse documents local saving as well as account-backed online projects; its groups and assignments require login. Tinkercad’s normal project workflow uses an Autodesk account.

Primary Sources

• DigiSim product FAQ, features, and pricing
• CircuitVerse key features, educator workflow, testbench documentation, and MIT-licensed repository
• Autodesk Tinkercad Circuits and Autodesk circuit-design overview
• Falstad Circuit Simulator and CircuitJS1 repository
• Logisim Evolution repository and Digital repository

If a material feature or pricing claim has changed, contact us. We will verify it against a primary source and record substantive corrections through the article’s update date.