Terms and Conditions

Last updated: August 11, 2026

These Terms and Conditions ("Terms") govern your use of rungs.dev, learn.rungs.dev, and studio.rungs.dev (the "Service") operated by Techsolid Automation Limited ("we", "us", "our"). By using the Service, you agree to these Terms.

The Service

rungs.dev is a browser-based PLC programming environment for creating, editing, simulating, and testing Add-On Instructions (AOIs) using Structured Text and Ladder Logic. The editor itself runs in your browser. Most of your work — projects you build in the user-mode editor and the library — is stored locally in your browser and is not uploaded to our servers unless you use the Share feature.

The exercise flow is different: when you run tests in an exercise on studio.rungs.dev, we save a snapshot of that exercise's AOI to our database so you can resume the exercise on another device. See "Your Content" and the Privacy Policy for details.

No Warranty — Not for Production Use

The Service is provided "as is" and "as available" without warranties of any kind, whether express or implied.

IMPORTANT: The Service is an educational and development tool. It is NOT certified for use in industrial control systems, safety-critical applications, or production PLC environments. You must not rely on simulations or test results from this Service as validation for real-world PLC deployments. Always verify logic independently using certified tools before deploying to physical hardware.

We do not warrant that:

The Service will be uninterrupted, error-free, or available at all times
Simulation results will be accurate or match the behaviour of any specific PLC platform
Your locally stored data will be preserved (browser storage can be cleared by the browser or operating system at any time)
Exercise progress stored on our servers will be preserved indefinitely (see "Accounts and Sign-in" for retention)

We create an anonymous Supabase account for you automatically on first visit so exercise progress can be saved; anonymous accounts and their data are pruned after 180 days of inactivity. You can upgrade to a permanent account by signing in with Google or GitHub, which moves your anonymous progress onto the permanent account. You agree not to operate multiple accounts to circumvent rate limits, and you can request deletion at any time by emailing privacy@rungs.dev. We may suspend or terminate accounts that violate these Terms.

Communications

By creating a permanent account (signing in with Google or GitHub), you agree that we may send you service-related emails — operational notices, security and retention warnings, material changes to these Terms or the Privacy Policy, and replies to your requests — for as long as you hold the account. We may also send occasional messages asking about your experience with the Service; these and any optional product-update or newsletter emails include a one-click unsubscribe link, and unsubscribing does not affect your account or service emails. We send marketing or newsletter emails only to users who have explicitly opted in. See the Privacy Policy for the lawful basis and how to opt out.

Your Content

Ownership

You retain full ownership of the AOIs and programs you create using the Service. We claim no rights over your content.

Exercise snapshots

When you run tests on an exercise on studio.rungs.dev, we store a copy of the AOI you have open for that exercise (tags, routines, and tests) against your Supabase account.

These snapshots are private — they are not shared with other users. We may read exercise snapshots only to investigate and fix Service or exercise issues.
You grant us a limited, non-exclusive licence to store, transmit, and process the snapshot only to provide the exercise resume feature and to operate the Service. We do not use exercise snapshots to develop, evaluate, or train machine learning or AI features.
A snapshot is overwritten each time you run tests on that exercise. The latest snapshot is the one we retain.
You can delete snapshots by deleting your account, or, for anonymous accounts, by waiting for the 180-day inactivity prune.

Shared Content

When you use the Share feature:

Your AOI is uploaded and made publicly accessible — anyone with the link can view and fork it
You represent that you have the right to share the content and that it does not violate any third party's intellectual property rights
You grant us a non-exclusive, worldwide licence to host, display, process, and use the shared AOI to operate, secure, and improve the Service, including developing, evaluating, and training machine learning and AI features
We may remove shared content at our discretion, including content that violates these Terms

Prohibited Content

You must not share AOIs, or paste content into Relay, that:

Contain malicious code or are designed to cause harm
Infringe on intellectual property rights of others
Contain confidential or proprietary information belonging to a third party
Contain personal data of other individuals
Contain secrets, credentials, or customer data

AI Features (Relay)

Relay is the AI tutor available in Studio's right sidebar. By using Relay, you agree to the following:

Educational only. Relay's replies are unverified suggestions from a large language model. They are not professional engineering advice, and they are not certified for use in industrial control or safety-critical applications. Always verify any code, instruction, or claim Relay produces using Studio's own compile, simulate, and test tools, and against authoritative manufacturer documentation.
Replies can be wrong. Like any AI assistant, Relay can produce incorrect, incomplete, or out-of-date answers, including answers about Studio itself. Treat them as a starting point, not a finished solution.
Your input is sent to a third-party model provider. When you send a message, Studio sends your prompt and your current AOI's tags and code to our studio-assist server, which forwards them to a third-party large language model provider. See the Privacy Policy for details on what is sent, the current provider, and how data is retained.
Traces are reviewed. We capture and store each Relay turn (prompt, reply, model, latency, anonymous session identifier, studio mode, and any feedback) for service quality and improvement, and we may read individual turns when investigating bugs or evaluating Relay's behaviour.
Free during early access. Relay is currently free. We may introduce paid AI features later, with separate billing terms posted before they take effect.

Paid Access and Billing

Most of the Service is free. Some exercises on rungs.dev require a paid access pass ("Plus").

Purchases are processed by Paddle. Paddle acts as our merchant of record: your order is placed with Paddle, which charges your payment method, applies any taxes such as VAT, and issues your receipt. Paddle's buyer terms apply to the transaction.
What you get. A pass unlocks every paid exercise in the catalog for 12 months from the date of purchase, including exercises we add to the catalog during that period.
One-time payment, no auto-renewal. A pass is a single payment. It does not renew automatically and we store no payment method. When it expires, paid exercises lock again; your progress is retained and free exercises remain available.
Sign-in required. A pass is bound to a permanent account (Google or GitHub sign-in) so it can follow you across devices. It is personal to you and may not be shared or transferred.
Refunds. See our Refund Policy.

Paid Exercise Content

Exercise prompts, starter AOIs, supplied solutions, tags, routines, tests, test data, and other materials we provide through Plus ("Paid Exercise Content") remain owned by us or our licensors. Plus grants you a limited, personal, non-exclusive, non-transferable licence to access, use, and export Paid Exercise Content during your access period for learning.

You may share individual exercise AOIs publicly or privately for genuine study, discussion, or collaboration, including your solution and the tests included with that exercise.

You must not sell, sublicense, mirror, or redistribute the complete paid exercise catalog or a substantial part of it, whether publicly or privately. You must not package Paid Exercise Content as a replacement for Plus access.

Acceptable Use

You agree not to:

Attempt to disrupt, overload, or interfere with the Service
Circumvent rate limits, bot-detection challenges (Turnstile), or other technical restrictions
Use automated tools to scrape or bulk-download content from the Service
Use the Service for any unlawful purpose
Reverse engineer or attempt to extract source code beyond what is publicly available in our repository
Use the Service to generate or distribute content that violates the "Prohibited Content" section above

Data and Storage

Local storage (non-exercise work). Projects you build in the user-mode editor and the library are stored in your browser's localStorage. We do not back up or recover this data. You are responsible for exporting and backing up your own work.
Exercise snapshots. When you run tests on an exercise, we store the AOI snapshot on our servers as described in "Your Content".
Shared AOIs. Publicly shared AOIs are stored on our infrastructure. We may remove inactive shares or impose storage limits.
Analytics. We collect usage analytics and technical telemetry as described in our Privacy Policy.

Service Availability

We may modify, suspend, or discontinue any part of the Service at any time without notice. We are not liable for any loss resulting from service interruptions or changes, including loss of locally stored data or server-side exercise snapshots.

Intellectual Property

The Service, including its design, code, documentation, and branding, is owned by Techsolid Automation Limited. The rungs.dev name and logo are our trademarks.

No right to access, copy, or use our source code is granted unless explicitly provided in a separate written licence agreement.

Limitation of Liability

To the maximum extent permitted by law, Techsolid Automation Limited and its directors, employees, and affiliates shall not be liable for any indirect, incidental, special, consequential, or punitive damages, or any loss of profits, data, or business opportunities arising from your use of the Service.

Our total liability for any claim arising from your use of the Service shall not exceed the amount you have paid us in the 12 months preceding the claim (which may be zero if you use the free tier).