Terra vs Open Wearables: Managed API or Self-Hosted Open Source?

This is not two vendors with different price sheets. Terra is a managed API you pay for; Open Wearables is MIT-licensed software from Momentum that you deploy and run yourself, with an optional paid Enterprise tier. Everything below is from Terra's pages, Open Wearables' site, docs and GitHub README as we read them on October 17, 2026.

At a glance#

Where Terra wins#

Nothing to run. Terra is a hosted service: "Subscriptions start from $399 per month billed annually, or $499 per month billed monthly." Open Wearables' core is free, but "A managed cloud version is not currently available", so hosting, monitoring, security patches and upgrades are yours.

Fewer provider applications. "Terra manages API Keys of data sources, meaning you can connect users without having to apply for each API Key", and its homepage says "Garmin data flows through Terra today" through a long-standing partner integration, although its integrations table still marks Garmin as Required. With Open Wearables, "Cloud providers require you to register with each developer program and obtain credentials"; its docs say "You must apply for Garmin Developer Program", and approval "ranges from immediate to several weeks depending on the provider."

Breadth beyond wearables. Terra supports Dexcom, orders blood and DNA tests, and delivers straight into databases, cloud storage and queues. Open Wearables says Dexcom is on its roadmap with no committed date and "does not natively output FHIR resources."

Outbound delivery documented today. "Every webhook sent by Terra includes an HMAC-based signature header", and Terra "retries the delivery up to 10 times with exponential backoff".

Where Open Wearables wins#

No licence fee and no per-user bill. Its docs put it as "Self-hosted, MIT license, $0 per user", and the pricing FAQ says you can "ship it in a commercial product at no cost." Terra's bill grows with every connected data source: "An active authentication is one connected data source for one end user, and costs 200 credits per month".

Data that never leaves your servers. Open Wearables' FAQ says "there is no third party holding your users' health records, and no data processing agreement needed with us because we never receive the data." It does send "a small anonymous usage ping once a day (plus one on startup)", which "contains only aggregate, bucketed counts and configuration flags, never health data, user data or credentials", and the README documents how to turn it off.

Open scoring and an MCP server. "Two documented scores ship with the platform": a nightly 0 to 100 Sleep Score and a weekly 0 to 100 Resilience Score derived from heart rate variability, and "An MCP server exposes scores, trends, and baselines to any LLM." Terra sells health scores as an add-on and offers an MCP server of its own through its AI Interface.

Webhooks: check the release you deploy#

Open Wearables' own pages disagree. Its README says you can "Register HTTPS endpoints to get notified when new data arrives for your users. Filter by event type or user, verify signatures, send test events, and inspect delivery attempts." Its FAQ says "Outbound webhooks (pushing events to your backend when new data arrives) are in active development", and its webhooks page says they "are still in development, so plan around reading from the API for now." The README lives with the code, but confirm in the release you pin. The README itself says "In production, pin the official images to a specific release version".

On Open Wearables' comparison page#

Open Wearables publishes its own comparison, which says it "covers the same provider set" as Terra and describes Terra as charging "a monthly fee plus per-API-call credits". By the two vendors' own pages that is not quite right today: Open Wearables lists no Dexcom or lab ordering, and Terra's pricing page bills credits for connected data sources and for events past a free allowance, not for API calls.

Compliance#

Self-hosting moves the compliance work to you rather than removing it. Open Wearables' Enterprise plan lists "SLA-backed support HIPAA-eligible infrastructure BAA and GDPR documentation", and its pricing FAQ says the "BAA is available on the Enterprise plan alongside HIPAA-eligible infrastructure and audit trail configuration." Terra says it "is HIPAA compliant, GDPR compliant, and SOC 2 Type II certified" and lists a signed BAA on Enterprise. Whether you need one depends on your role under HIPAA; our HIPAA compliance guide for fitness apps explains when that applies. This is general information, not legal advice.

Which should you pick?#

• Health data must stay on infrastructure you control, and you have the engineers to run it: Open Wearables.
• You want to ship this quarter without registering with every provider: Terra, after checking its credential list for your providers.
• Dexcom, lab tests or delivery into your warehouse: Terra.
• Many users, each a cost on a per-source bill: model both; Open Wearables has no licence fee, but price your own hosting and on-call before calling it cheaper.
• Custom scoring logic you can read and retune: Open Wearables.

For managed alternatives, see health-data aggregator APIs and the Terra integration guide.

Bottom line#

Terra sells breadth and convenience by the connected source; Open Wearables gives you the code and the responsibility. Pick by who should run the stack and hold the provider relationships, then re-check both projects' live pages, because Open Wearables' APIs are still pre-1.0 and Terra's prices are as of October 17, 2026.