Terms of use
Last updated 14 October 2026. These terms cover the Grainmark service at grainmark.app, its API and its MCP endpoint, whether you use them in a browser, with an API key, or through an AI agent. Grainmark is operated by Hoopes Group LLC, an Oregon limited liability company (Oregon Business Registry No. 263985690); "we" and "us" in this page mean Hoopes Group LLC.
What the service does
Grainmark seals media you upload and later compares copies against that seal.
A result is an unsigned visual comparison against one specific earlier seal.
It is not a signature, not OCR, and not a judgment on
whether media was AI-generated. A confirmed timestamp proves the seal existed no later than Bitcoin block time T. It does not prove who captured the media, when it was captured, or that it was sealed at capture. A PARTIAL result is inconclusive.
Do not present a Grainmark result as more than that.
Your media
- Only upload media you have the right to upload.
- Seals are private until you publish them. Publishing makes the seal's metadata and its sidecar, including embedded probe images of the media, public.
- How uploads and sidecars are stored and deleted is described in the privacy policy.
Acceptable use
- Stay within the published rate limits and upload caps. Do not use several keys or addresses to get around them.
- Hourly and daily limits are a ceiling against abuse, not reserved capacity. Grainmark may throttle abusive traffic inside those numbers.
- Do not try to read seals that are not yours, probe for private seals, or disrupt the service for other users.
- Do not upload unlawful content.
API keys
Keys are issued at our discretion, carry specific scopes, and can be revoked at any time. Keep a key secret; you are responsible for calls made with it.
Billing
Paid and free API keys are subscriptions billed by Stripe. Cancellation is through the Stripe customer portal. The refund policy is not set.
No warranty
The service is provided as is, without warranty of any kind, and may change, be interrupted, or be withdrawn. Seals and results may be lost. Do not rely on Grainmark as your only record of anything. To the extent the law allows, we are not liable for losses arising from use of the service or reliance on a result.
Changes and contact
We may update these terms; the date above changes when we do. Questions: hello@rick3.dev.