Teams pay for API plans every month and rarely use them up. Surplus lets them sell the spare capacity — so you can buy the same calls below list price, through one key and one balance. If no seller can serve a call, the fallback catalog answers instead.
# POST /v1/rpc/solana — routed to the cheapest healthy offer curl https://api.surplus.dev/v1/rpc/solana \ -H "Authorization: Bearer spl_live_a1b2c3…" \ -H "Content-Type: application/json" \ -d '{"jsonrpc":"2.0","id":1,"method":"getAssetsByOwner", "params":{"ownerAddress":"9xQe…","page":1,"limit":10}}'
# response headers — the receipt, in the envelope X-Surplus-Route: market X-Surplus-Offer: ofr_sol_1 X-Surplus-Units: 10 X-Surplus-Charged-Usd: 0.000042 X-Surplus-Billing-State: settled Charged $0.000042 · settled
Most companies prepay for API capacity every month and rarely finish it — think of a gym membership, but for software. Surplus lets them sell the part they won’t use. Buyers get the very same calls for less than list price, and every request comes with a receipt, so you can always check the math.
Three steps, no provider accounts, no plan juggling.
Post a funding intent, credit the workspace. One balance pays every route; money is integer micro-USD, so rounding never drifts.
Least-privilege scopes — rpc:execute, tools:execute, usage:read — plus a monthly budget and a per-request ceiling baked into the key.
The router picks the cheapest healthy offer for the route. Funds are held before execution, settled after, and every outcome lands on a receipt you can recompute.
Most team plans die at the end of the month with capacity left on the table. Listing it takes three decisions:
Every seller signs a provider-terms attestation: the credential’s terms must permit resale or shared-seat access, and the listing displays the provider’s resale notice next to the ask.
Every offer shows its ask, the dated list price it beats, and the fee separately. You can recompute any receipt from public numbers.
Drag the slider. The ask side is live from the market — the cheapest healthy offer on the route right now.
Assumes ~10 credits per call. Platform fee (5%) is charged on top of the ask and shown separately on every receipt.
| State | Meaning |
|---|---|
| held | Funds reserved at min(quote, per-request ceiling) before the call runs. Nothing has moved yet. |
| settled | The request completed; actual units were charged and the remainder of the hold released. |
| voided | The call failed or was refused before execution; the hold is released in full. You pay nothing. |
| under_review | A settle disagreed with the quote. Funds stay locked pending review; auto-refund after the review window. |
Daily and monthly caps at the account level. When the cap trips, calls refuse cleanly instead of running up a bill.
Each key carries its own monthly budget. A runaway CI job burns its own allowance, never the workspace’s.
A single call can never settle above the key’s ceiling — the hold itself is capped, so overshoot is structurally impossible.
Phase 0 runs at $0. The roadmap shows what the next phases buy. Read the full roadmap →