Users never register twice
A person who already has a HarperHarbor account signs in to your app with one tap. Their balance comes with them.
Open API v1 · Beta
One account and one wallet, across every companion product you ship.
Users sign in once and pay once. Your app ships features — not billing, identity or model plumbing. Built for companion, virtual-being and interactive-story products.
#100001
One user
Wallet8,253 pts
−12 pts−8 pts
Ychat.play
Your app
Achat.play
Another app
One bill
| 09:41 | Your app · chat.play | -12 |
| 09:38 | Another app · chat.play | -8 |
| 09:12 | Your app · chat.play | -21 |
Balance8,253 pts
We built this to run our own products first. Now it is open.
The same account, wallet and model lanes that power our own chat stage and community tavern are what you integrate. No separate "partner" tier.
What changes for your product
You never touch money
Top-ups, refunds, disputes and receipts are the platform's problem. Your app reads a balance and makes calls.
Switching models is not a deploy
Every model sits behind a named lane with automatic failover. When an upstream degrades, traffic moves and the user is told.
Under the hood
Six things every companion product needs and none should build twice.
Identity and wallet
One account, one prepaid balance, shared across apps. Apps are groupings of users, never owners of them.
Persona runtime
Card play, greetings, author display rules and memory, exposed as services rather than a single product's chat screen.
Model lanes
Several upstreams behind each model, published as stable codenames. Routing, health probes and failover are ours to run.
Boundaries
Fixed roles, app-scoped queries enforced server-side, upstream names never exposed, every admin action audited.
Metering
Every call is an event with user, app, service and lane. Daily rollups reconcile against the wallet, and the delta must be zero.
Open API and MCP
A frozen v1 contract with OAuth 2.1 for people, and read-only MCP tools for AI clients — same service layer, same rules.
The console is already running
Attention first, then numbers: lane health, quota pressure and reconciliation on one screen. What you see here is the same console your team will use.
For developers
Register once, exchange a code, make a call. The contract is frozen at v1 and any language works.
AI clients can also read usage and lane status over MCP with the same token.
Open the quickstart# 1. exchange the authorization code (PKCE)
curl -X POST https://api.harperharbor.com/oauth/token \
-d grant_type=authorization_code -d code=$CODE \
-d client_id=$CLIENT_ID -d redirect_uri=$REDIRECT_URI \
-d code_verifier=$VERIFIER -d resource=https://api.harperharbor.com/open/v1
# 2. who is signed in
curl https://api.harperharbor.com/open/v1/me \
-H "Authorization: Bearer $ACCESS_TOKEN" \
-H "language: en"Pay per use. No monthly fee.
Users prepay points. Apps integrate for free. Rates are published per model and lane before anyone spends a point.
Users prepay points
Points do not expire. Every call debits the user's single wallet, whichever app made it.
Apps pay nothing
No seat fee, no revenue share, no minimum. The only limit is a daily quota that protects the platform.
Rates are public
Each model-and-lane price is shown in the console and inside the product at the moment of use.
Clear boundaries
- 01
An app sees only its own users
Never balances, never activity from other apps. The scope is enforced in the query, not in the UI.
- 02
Every admin action is audited
Who, when, what and through which channel — console, API, SSO or cron. Retained 180 days.
- 03
Users can leave
A user can revoke any app in one click; its tokens stop working immediately.
Questions
Is this a character-chat API?
Card play is the first service, but the product is the layer underneath: shared identity, one wallet, model lanes, metering and boundaries. Any companion-style experience can sit on it.
What if I want to bill my own users?
Then this is not for you yet. Apps on HarperHarbor do not charge or settle; that is the trade for never touching money. Settlement is on the roadmap, not a promise.
Which models do you run?
We publish lanes, not vendor names. A lane is a stable codename with live health and a price; behind it we may run several upstreams and move traffic between them.
Ship the product. Skip the plumbing.
Apps are onboarded by the platform team in phase 1. Tell us what you are building.
Request access