Terms of Service

Free Tier: DigiSim offers selected lessons and simulator components at no cost, as currently configured. Browser-local persistence differs by lab: Logic keeps local circuits, Electricity, Analog and Relay each keep one local draft.

Pro: A recurring subscription (billed monthly or annually) that unlocks the complete current component and lesson catalogs. Cloud save, sharing, embeds, and project exports remain available only in labs that support those features. Pro renews automatically until you cancel; canceling stops future billing and you keep access through the end of the period you already paid for.

Founder: A limited-time one-time payment offer, available only while shown at checkout. It grants the same paid feature set as Pro, for as long as the Service remains operational, with no recurring charge — see "Access Duration" below for what this does and does not guarantee.

Classroom: Digital Logic Lab teaching through an annual per-seat subscription purchased in Checkout or an administrator invoice. The minimum seat count, price and billing terms are shown before purchase. Self-service subscriptions renew annually until canceled; administrator-invoice orders also follow their accepted terms. Other labs are outside the Classroom teaching scope.

Grandfathered Purchases: If you previously bought a one-time tier, SimCast Set, or Bundle under an earlier pricing model, that purchase remains valid under these Terms — no new subscription is required, and nothing you already own is taken away.

DigiSim.io provides an interactive, web-based platform for learning, creating, and simulating digital logic, relay, electricity, and analog circuits. The Service includes SimCast lessons, four purpose-built circuit simulators, lab-specific browser persistence, optional cloud storage where supported and subject to plan quotas, and related educational tools. Logic keeps browser-local circuits, Electricity, Analog and Relay each keep one local draft. Project-file export is available only where the selected lab supports it, with formats and extensions that can differ by lab and version. The Service is designed for educational purposes to help students, hobbyists, and professionals understand circuit and electronics principles.

Account Creation: An account is required for paid entitlements, cloud saves, account-managed sharing and Classroom. Selected public features and supported browser-local work can be used without an account. Provide accurate information needed for registration and keep it current.

Account Responsibility: You are responsible for safeguarding your account credentials and for any activities or actions under your account. You agree to notify us immediately upon becoming aware of any breach of security or unauthorized use of your account.

One Account Per Person: Each user may maintain only one account. Creating multiple accounts to circumvent usage limits, abuse free tier allowances, or exploit promotional offers is prohibited.

Children and Students: People under 18 must have the authority and permission required by applicable law. A child under 13 must have authorization from a parent or legal guardian to create a personal account, together with any legally required permission. School approval does not automatically replace parental responsibility or consent where the law requires it. Schools arranging access must have authority to invite students and provide appropriate notices. The Privacy Policy explains the limits of the standard signup flow and how to raise a child-privacy concern.

Third-Party Authentication

Google Sign-In:

• Firebase Authentication handles DigiSim sign-in; the Service currently offers email-and-password and Google sign-in
• By using Google Sign-In, you agree to comply with Google's Terms of Service
• Google sign-in requests only OpenID, email and basic profile information (name and profile picture where available)
• You can manage or revoke DigiSim.io's access to your Google account at any time through your Google Account settings

Authentication Security:

• DigiSim does not receive or store your Google password or access Google content such as Drive or Gmail
• Email-and-password credentials and Google authentication are managed by Firebase Authentication
• Firebase may retain sign-in state in browser IndexedDB until you sign out or clear browser data

Account Linking:

• A Google sign-in account is linked to the verified email address and provider identifier supplied through Firebase
• You are responsible for maintaining the security of your Google account
• If your Google account is compromised, please immediately change your Google password and contact us

Nature of Purchase

A purchase grants a limited, non-exclusive and non-transferable licence to access the applicable digital Service features for the period and plan shown before checkout. It does not transfer ownership of DigiSim source code, lessons or other DigiSim intellectual property. We may suspend or end access only as these Terms fairly permit, and mandatory consumer remedies remain available.

Access Duration

Access depends on the order. Subscription plans (Pro and, where offered, Classroom): access covers the paid subscription period and any stated payment-retry grace period. One-time purchases (Founder and grandfathered products): access has no recurring charge and continues while the relevant Service is operated and the account remains in good standing. "One-time" describes billing; it is not a promise that an online service will operate forever. If we discontinue a material paid service, we will give reasonable notice where possible, provide available export tools and give any remedy required by law.

Subscription Billing

Pro subscriptions renew automatically for the period shown at checkout until canceled. Self-service Classroom subscriptions renew annually per seat until canceled. You may cancel through the account billing controls or Stripe customer portal; cancellation normally takes effect at the end of the current paid period and stops future renewals. Charges for a period already started are not routinely prorated, but this does not limit cooling-off rights, remedies for faulty or misdescribed digital content or services, or any other mandatory right. If payment fails, Stripe or DigiSim may retry it and access may lapse after any stated grace period. Classroom billing uses the accepted seat count; administrator-invoice orders also follow their accepted order terms.

Free Tier

The free tier provides the components, lessons, cloud quota and share-link allowance shown in the current Service. We may change a free feature as the product evolves. Where a change materially affects active users, we will try to give reasonable notice, but free features do not create a paid entitlement.

No Transfer or Resale

Purchased licenses are personal to the account holder and may not be transferred, resold, shared, or assigned to another person or entity. Account credentials must not be shared with others.

Future Content

A purchase includes the plan and material features described before checkout. We may add content and may sell later products separately. Unless the order expressly says so, a purchase does not include every future product, but we will not use catalog maintenance to remove the essential benefit of a paid order without a fair reason and any remedy required by law.

Tier Access, Not Fixed Catalog

A plan gives access to the maintained catalog for that tier, not an immutable snapshot of every item. We may add, correct, replace, merge or withdraw individual lessons, templates or components for security, accuracy, pedagogy, duplication or licensing reasons. We will preserve the plan's essential paid functionality and apply any statutory conformity or refund remedy where a change means the Service no longer matches the contract.

Pricing Changes

We may change prices for future orders. A change does not alter a completed one-time purchase. Before a subscription price increase applies, we will give at least 30 days' notice and explain how to cancel before renewal. Promotional pricing and the Founder offer may be withdrawn for new orders at any time while they remain clearly described before checkout.

Payment Processing

Stripe provides hosted checkout, payment processing, invoices, subscription management, fraud controls and refunds. Payment details are entered on Stripe's hosted surface; DigiSim does not store full card numbers or card security codes. Tell us promptly about a duplicate, unauthorised or incorrect charge so we can investigate with Stripe. Nothing here excludes responsibility DigiSim has under applicable law.

Refunds

Cooling-off rights, digital-content and service remedies, commercial review criteria and the request process are set out in our Refund Policy. That policy does not reduce mandatory consumer rights.

Your Content: You retain all ownership rights to the digital circuits, designs, and other content you create or save while using the Service ("User Content"). Browser-local persistence differs by lab. If you use cloud save, an unlisted link, or the public gallery, the applicable circuit data is also stored on our servers as described in our Privacy Policy. Anyone with an unlisted URL can view it. Use a project-file export to keep an independent copy only where that lab provides one.

License to Us: You retain ownership of your work. When you upload or explicitly submit content through cloud save, sharing, public publishing or an enabled Classroom feature, you grant DigiSim a non-exclusive, royalty-free license to store, copy, process and display it only as needed to provide that feature, follow your sharing choices, maintain its reliability and security, and meet legal obligations. This license does not make private work public or authorize unrelated reuse. Reading a template or playing a DigiSim lesson does not itself upload your private circuit.

Public Gallery: If you publish a circuit to the public gallery, its name, your DigiSim username, any description you add, a thumbnail, and the circuit design become visible to anyone without an account, in a searchable public listing. You are responsible for ensuring anything you publish complies with these Terms and does not infringe third-party rights. We may remove published content that violates these Terms, and you can unpublish your own content at any time.

Exported Files: Project files you export are your own data. Format and extension differ between labs (for example, Logic, Relay and Analog use different project formats) and compatibility can change by version. You may store and share the files, and we make no ownership claim over copies kept outside the Service.

Responsibility: You are solely responsible for your User Content and represent that you have all necessary rights to use any content you design within the Service. You must not attempt to store content that infringes third-party intellectual property rights.

DigiSim.io provides computing resources for circuit simulation, supported cloud storage, sharing, and SimCast playback. Browser-local persistence is lab-specific and browser storage is finite and controlled by the browser. Cloud-saved circuits and links are subject to the feature and plan rules below. Server resources are shared, so fair use is required.

Storage and Share-Link Quotas

Logic keeps browser-local circuits, Electricity, Analog and Relay each keep one local draft; browser storage remains subject to browser capacity and eviction. Where cloud save is supported, current limits are 5 on Free and 250 on Pro or Founder. Logic and Electricity unlisted links are limited to 2 simultaneously active on Free and 50 on Pro or Founder, expiring after 14 or 365 days respectively; anyone with the URL can view them. Relay uses a separate revocable public-link model, and Analog sharing is not currently documented. Classroom quotas apply only as stated for a confirmed Classroom entitlement. Project-file and image exports are available only where a lab supports them; you control destination storage.

Prohibited Activities

You agree not to use the Service for:

• Bulk/Automated Creation: Using scripts, bots, crawlers, or automation tools to generate, upload, or download massive quantities of files or data.
• Non-Circuit Data: Using project storage for unrelated files or data outside the supported circuit-simulation and learning features, for example treating project metadata as a general-purpose file host.
• Excessive Load: Creating an abnormal volume of projects, simulations, or API requests that exceeds reasonable human operation (e.g., hundreds of creations per day).
• Resource Exploitation: Using SimCast playback, audio generation, or simulation resources in a manner designed to consume excessive server resources.
• Credential Sharing: Sharing account credentials with others to allow multiple people to access purchased content through a single account.
• Content Scraping: Systematically downloading, copying, or redistributing SimCast lesson content, narration audio, or simulation data.

Enforcement

If we reasonably detect abuse, bot activity, credential sharing or resource exploitation, we may proportionately throttle requests, suspend write access, restrict the affected feature or terminate a materially breaching account. We will normally explain the reason and give an opportunity to correct the issue unless immediate action is reasonably needed for security, law or harm prevention. Any refund consequence remains subject to the Refund Policy and mandatory rights.

Monitoring

We process usage patterns, storage totals and API activity as described in the Privacy Policy to enforce these Terms, maintain service quality and detect abuse. Private circuit content is accessed only where needed to provide a feature you request, investigate a specific technical or security issue, enforce these Terms proportionately, or comply with law.

You agree not to misuse the Service or help anyone else to do so. You agree not to:

• Probe, scan or test systems without authorization, except to the extent applicable law gives a right that cannot be excluded
• Breach or otherwise circumvent any security or authentication measures
• Access, tamper with, or use non-public areas of the Service, its systems, or its infrastructure
• Interfere with or disrupt any user, host, or network, including by sending viruses, overloading, or flooding the Service
• Use the Service for any illegal or unauthorized purpose
• Reverse-engineer, decompile or disassemble the Service except where permitted by applicable law or a relevant license
• Copy, redistribute or create derivative works from DigiSim materials beyond the rights granted by the relevant license or applicable law
• Use automation outside documented APIs or the reasonable public indexing and user-requested retrieval permitted by our published robots.txt and LLM guidance. That permission does not authorize access to private routes, bypassing access controls, excessive load, prohibited bulk copying or model training beyond the published permissions and applicable law.
• Impersonate another person or entity, or falsely state or misrepresent your affiliation
• Attempt to gain unauthorized access to other users' accounts or data

The Service and its original content — including but not limited to SimCast lessons, narration audio, animation sequences, circuit templates, component designs, user interface, logos, and documentation — are and will remain the exclusive property of DigiSim Technology Ltd and its licensors. The Service is protected by copyright, trademark, and other intellectual property laws. Our trademarks and trade dress may not be used in connection with any product or service without our prior written consent. Purchasing content licenses does not transfer any intellectual property rights to you.

No Guarantee of Perfection: The Service is a complex software system under continuous development. While we strive to provide a reliable, high-quality experience, we do not guarantee that the Service will be uninterrupted, error-free, secure, or free of bugs, defects, or vulnerabilities at all times.

Educational Simulation Platform — Not for Safety-Critical Use: DigiSim provides four educational circuit-simulation labs for digital logic, relay, electricity, and analog subjects. It is not designed or licensed for use in safety-critical, life-critical, medical, aviation, automotive safety, nuclear, or industrial control systems. You must not rely on any simulation output, timing characteristic, or component model for decisions that could result in personal injury, property damage, or financial loss without independent hardware validation, professional engineering review, or other appropriate safeguards.

Simulation Accuracy: Circuit simulations are educational approximations built to illustrate the electrical or digital principles identified by each lab's published component specifications. They are not a substitute for hardware validation, bench testing, production-grade device models, or professional engineering judgment. Simulations may not perfectly replicate real-world hardware behavior, timing, tolerances, parasitics, or analog effects. DigiSim does not guarantee the accuracy of simulation results for any purpose, including academic assessment or professional engineering.

Content May Contain Defects: We strive to implement components, SimCast lessons, templates and examples in accordance with established principles, but software can contain bugs, edge cases or deviations from idealised behaviour. We may correct defects through updates or replacements. The Refund Policy and applicable law govern any repair, repeat performance, price reduction or refund right.

What We Do Not Provide: Unless specifically and separately purchased, DigiSim does not provide: (a) certification, accreditation, or recognition by any educational, industry, or professional body; (b) one-to-one tutoring, personalized learning plans, or human instruction; (c) guarantees that the Service will help you pass any exam, course, or qualification; (d) one-to-one engineering consulting or custom development as part of educational content; ordinary account, billing and defect reports can be sent to support; (e) any warranty that the platform, content, or outputs are suitable for any particular purpose beyond the educational circuit principles stated for the selected lab.

Data Integrity: We use reasonable measures to protect server data and maintain operational backups, but local browser data and online services can be lost or disrupted. Keep independent copies where the selected lab provides export controls. Our responsibility for data loss is governed by the fair liability terms below and cannot be excluded where law does not permit it.

Maintenance Windows: We may perform scheduled or emergency maintenance that temporarily interrupts the Service. We will make reasonable efforts to provide advance notice for planned maintenance.

Bug Reports: Report faults to support@digisim.io with enough information to reproduce them and without sending passwords or payment-card details. We do not publish a general response-time or fix-time SLA. This does not limit the reasonable-time remedy obligations described in the Refund Policy or any mandatory right.

By You: You may stop using the Service, cancel a subscription or request account closure at any time. Subscription cancellation and account deletion are separate actions. The Privacy Policy explains what is deleted, what you should export or remove first, and what limited records may lawfully remain.

By Us — For Cause: We may suspend the affected feature or terminate an account for a material or repeated breach, fraud, security risk, unlawful conduct or serious harm. Except where urgent action is reasonably necessary, we will give notice, explain the reason and allow a reasonable opportunity to correct a remediable breach.

Service Discontinuation: We may discontinue or substantially change a Service for a genuine business, legal, security or technical reason. We will give reasonable advance notice where practicable, preserve available export tools and provide paid users any cancellation, price-reduction or refund remedy required by law.

Effect: Access to the terminated feature ends when the termination takes effect. Where reasonably possible and safe, we will provide a limited opportunity to export private content before deletion. Public content may be removed immediately where it creates risk or violates these Terms.

Refunds After Breach: A user terminated for a material breach is not entitled to a discretionary refund merely because access ended, but this does not remove a mandatory statutory remedy or a refund unrelated to the breach.

Survival: All provisions of the Terms which by their nature should survive termination shall survive termination, including ownership provisions, warranty disclaimers, limitations of liability, and indemnity obligations.

We will provide paid digital content and services with the quality, fitness, description and reasonable care required by applicable law. Because DigiSim is evolving software, we do not promise uninterrupted availability or that every educational model will reproduce every real-world effect. These limits do not override an express description at checkout or a mandatory guarantee.

DigiSim is an educational simulator, not a substitute for professional engineering review, physical testing or a safety system. Do not use an output as the sole basis for a medical, life-safety, aviation, automotive-safety, nuclear, industrial-control or other decision where error could cause injury, property damage or material financial loss.

Consumers: Nothing in these Terms excludes or limits liability for death or personal injury caused by negligence, fraud or fraudulent misrepresentation, breach of statutory digital-content or service rights, or anything else that cannot lawfully be excluded. Subject to that, we are responsible for loss that was a foreseeable result of our breach or failure to use reasonable care, but not business losses suffered by a consumer or loss caused by your misuse or failure to follow reasonable instructions.

Business and institutional users: Nothing excludes liability that cannot lawfully be excluded. Subject to that, neither party is liable for indirect or consequential loss, and DigiSim's total aggregate liability arising from the Service in a 12-month period is limited to the greater of the fees paid for that Service during that period or £100. This business cap does not apply to payment obligations, infringement caused by a party's own content, fraud, deliberate misconduct or a separately signed agreement that states a different cap.

This section applies only if you use the Service for a business or institution. You will reimburse DigiSim for reasonable, finally awarded or agreed losses arising from a third-party claim caused by your unlawful User Content, your infringement of that third party's rights, or your deliberate material breach of these Terms, provided we notify you promptly, allow reasonable control of the defence and cooperate. This section does not apply to consumers and does not make you responsible for DigiSim's own acts.

Contact first: Please contact support so we can try to resolve a complaint promptly. This does not stop either party seeking an urgent remedy or using a statutory complaint process.

Consumers: These Terms are governed by the law of England and Wales, but you keep mandatory protections of the country where you habitually live. You may bring a claim in a court available under applicable consumer law; these Terms do not require a consumer to litigate only in England.

Business users: The courts of England and Wales have exclusive jurisdiction and the law of England and Wales applies, unless a separately signed agreement says otherwise.

We may update these Terms for legal, security, technical or product reasons. We will post the new date and give at least 30 days' notice by email or a prominent in-Service notice before a change that materially disadvantages an existing paid user, unless an urgent legal or security change requires faster action. A change will not retrospectively alter a completed charge or remove a mandatory right. If you do not accept a prospective change, you may stop using the Service and cancel future renewals before it takes effect; any additional termination or refund right required by law remains available.

If a provision is invalid or unenforceable, it will be limited only as much as necessary and the rest remains effective. These Terms, the order information shown before checkout and the policies they link to form the agreement for the Service. Nothing in this section excludes liability for fraud or fraudulent misrepresentation, or a mandatory pre-contract statement or consumer right.

If you have any questions about these Terms, please contact us: