> ## Documentation Index > Fetch the complete documentation index at: https://docs.pay.aptahq.com/llms.txt > Use this file to discover all available pages before exploring further. # Price a collection before charging > **What will this collection cost?** Returns the fee and the total the customer must pay, so a confirm screen can show real numbers before anyone commits. **This is a standalone call and holds no state.** It moves no money, needs no `Idempotency-Key`, and returns no token to redeem — quote as often as you like, or skip it entirely. The OTP -> charge flow never consults it, so a quote is never "used up" and can never expire out from under a customer. `total_to_pay_minor` comes from the provider, not from `amount_minor + fee_minor` computed here. Show that figure: it is what the customer is actually billed. **Amounts in and out are integer minor units**, and UGX/RWF/XAF/XOF are zero-decimal. `momo` and `bank` can be quoted; `card` cannot, and answers 501. ## OpenAPI ````yaml /openapi.json post /v1/collections/quote openapi: 3.0.3 info: title: AptaPay Gateway version: 1.0.0 description: > One provider-neutral payment API owned by many apps: collections, payouts, bank resolution and FX, with signed webhooks back. ## Authentication Every `/v1/*` request carries four headers. **A plain API key is not enough** — a key in a proxy log or an error report would be immediately usable, whereas a signature binds the request to a body and a moment. | Header | Value | | --- | --- | | `X-AptaPay-Key` | `{app_id}.{key_id}.{api_key}` | | `X-AptaPay-Timestamp` | unix seconds | | `X-AptaPay-Nonce` | 16-64 chars, `[A-Za-z0-9_-]`, unique per request | | `X-AptaPay-Signature` | `v1={hex HMAC-SHA256}` | The signature is HMAC-SHA256, with your **inbound** signing secret, over exactly these ten fields joined by `\n`: ``` v1 {APP_ID} {KEY_ID} {HOST} lowercased {METHOD} uppercased {PATH} no query, NOT url-decoded {CANONICAL_QUERY} sorted, RFC3986-encoded, "" when absent {TIMESTAMP} {NONCE} {SHA256_HEX(RAW_BODY)} sha256("") for GET/DELETE ``` Every field earns its place. `CANONICAL_QUERY` is in there because without it `?limit=1` and `?limit=100000` sign identically, so a captured read signature could be replayed to dump everything. `HOST` stops a signature captured against one deployment replaying into another. The timestamp window is **asymmetric**: `-120s <= now - ts <= +30s`. A symmetric window is a ten-minute replay window, and there is no legitimate reason to sign in the future beyond small clock skew. A working reference implementation is in `docs/TENANT_INTEGRATION.md`, and `scripts/sign_request.mjs` signs a request from the terminal. ## Idempotency `Idempotency-Key` is **required** on every money-moving POST. A missing key is a 400 — the server never invents one, because a server-generated key is unique per request and protects nothing, which is worse than none because it looks like protection. - Replaying a completed key returns the **original response verbatim**, with its original status code. No second provider call. - The same key with **different parameters** is a 422, never a replay. - A concurrent duplicate is a 409 `request_in_progress`. ## Errors Branch on `error.code` and the three booleans, never on the HTTP status: `terminal` (reverse and tell the user), `retriable` (retry with the same key), `ambiguous` (**do not reverse** — poll instead). ## Amounts Integer minor units, with a per-currency exponent. **UGX, RWF, XAF and XOF are zero-decimal**: 2000 UGX is `2000`. Getting this wrong is a 100x error. ## Test mode is NOT a sandbox **Every request reaches a real provider. There is no sandbox, and no test host.** AptaPay routes to a single upstream provider, and that provider publishes exactly one API host for live and test traffic alike. No sandbox base URL exists anywhere in its reference documentation. So "test mode" here does not mean what it means on Stripe. It is a **second, real provider account** holding a small real balance, reached over the same wire as production. A test-mode payout moves real money out of a real wallet to a real phone number. It cannot be reversed, because the provider exposes no refund endpoint. | | What you might expect | What actually happens | | --- | --- | --- | | Host | a separate sandbox host | the one production host, always | | Money | simulated | real, in a real wallet | | Recipients | fake numbers accepted | real MSISDNs, really credited | | Undo | reverse the test charge | none — no refund endpoint exists | Two guardrails stand in for the sandbox, and they are permanent, not temporary scaffolding: - **A hard amount ceiling on every test-mode transaction**, enforced by this gateway *before* any provider call. Over it, you get a `422` and no request ever leaves. - **`is_test_mode` stamped on every transaction record**, so a test transaction is identifiable forever after the fact. Mode is a property of **which credentials you hold**, never of a request field — there is no `test: true` to send, and no header that switches it. A live key transacts live; that is the only thing that decides it. See `GET /healthz` for which mode a deployment is running. ## CORS There isn't any, deliberately. This is a server-to-server API and browsers must never call it: signing from client-side JS would put your secret in view-source. Cross-origin browser requests are denied. servers: - url: https://api.pay.aptahq.com description: >- Production. There is no sandbox host, because the upstream provider has none — see "Test mode is NOT a sandbox". Sign the host you dial: the host is part of the canonical string, so a request dialled here must claim `api.pay.aptahq.com`. security: - AptaPaySignature: [] tags: - name: Collections description: Money in. - name: Payouts description: Money out. - name: Refunds description: Reversals — 501 where the routed provider has no refund endpoint. - name: Transactions description: The gateway's own ledger of what it was asked to do. - name: Beneficiaries description: Saved recipients. Stored masked, names re-resolved at payout time. - name: Reference description: Corridors, banks, countries, balances, capability matrix. - name: Float description: Your own claim on the shared wallet pool — what you can actually pay out. - name: FX description: Exchange between your own wallets. Quote is free; exchange moves money. - name: Webhooks description: Provider ingress. Documented for completeness; tenants never call it. - name: Ops description: Health. paths: /v1/collections/quote: post: tags: - Collections summary: Price a collection before charging description: > **What will this collection cost?** Returns the fee and the total the customer must pay, so a confirm screen can show real numbers before anyone commits. **This is a standalone call and holds no state.** It moves no money, needs no `Idempotency-Key`, and returns no token to redeem — quote as often as you like, or skip it entirely. The OTP -> charge flow never consults it, so a quote is never "used up" and can never expire out from under a customer. `total_to_pay_minor` comes from the provider, not from `amount_minor + fee_minor` computed here. Show that figure: it is what the customer is actually billed. **Amounts in and out are integer minor units**, and UGX/RWF/XAF/XOF are zero-decimal. `momo` and `bank` can be quoted; `card` cannot, and answers 501. operationId: quoteCollection requestBody: required: true content: application/json: schema: type: object required: - amount_minor - currency - country - method properties: amount_minor: $ref: '#/components/schemas/MinorUnits' currency: $ref: '#/components/schemas/Currency' country: type: string example: UG method: type: string enum: - momo - bank example: amount_minor: 20000 currency: UGX country: UG method: momo responses: '200': description: The fee quote. Nothing was reserved and nothing expires. content: application/json: schema: $ref: '#/components/schemas/APIResult' example: code: 200 message: OK data: amount_minor: 20000 fee_minor: 300 total_to_pay_minor: 20300 currency: UGX method: momo min_amount_minor: 500 max_amount_minor: 4000000 '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' components: schemas: MinorUnits: type: integer description: > An integer count of the currency's smallest unit. NEVER a float, and never a decimal major amount. The `_minor` suffix on a field name is part of the contract: `amount` could be read as `20.00` or `2000`, whereas `amount_minor` can only be read one way. **The exponent is PER CURRENCY.** There is no universal "cents": | Exponent | Currencies | `2000` means | |---|---|---| | **0** (zero-decimal) | UGX, RWF, XAF, XOF | 2,000 shillings/francs | | **2** | KES, GHS, NGN, TZS, ZMW, USD, EUR, GBP | 20.00 | So `2000` UGX is two thousand shillings, while `2000` KES is twenty. Applying a blanket x100 to a zero-decimal currency is a **100x money error** — the kind that reconciles to nothing months later. To send an amount, multiply the major amount by `10^exponent` and confirm the result is an exact integer (KES `19.99` -> `1999`). To display one, divide by `10^exponent` for presentation only — keep the minor-unit integer as the value you store, compare, and sum. Rules the gateway enforces: - **An unknown currency is rejected, never defaulted.** A currency with no declared exponent fails with `unknown_currency` rather than assuming 2, because a silent wrong exponent is worse than a loud failure. - **A non-exact amount is rejected, never rounded.** KES `19.999` fails with `inexact_amount`. AptaPay will not decide on your behalf which way to round someone's money. - **Amounts are never floats internally.** Providers send amounts as strings (`"2000"`) AND sometimes as numbers, so parsing is deliberate at the adapter boundary and converts to an exact integer or fails. A field's exponent always follows the currency named alongside it. On an FX quote, `source_amount_minor` and `destination_amount_minor` routinely use DIFFERENT exponents in the same response. example: 2000 Currency: type: string enum: - UGX - RWF - XAF - XOF - KES - GHS - NGN - TZS - ZMW - USD - EUR - GBP APIResult: type: object description: > The single response envelope, used by EVERY endpoint so a consuming app parses one shape everywhere. required: - code - message properties: code: type: integer example: 200 message: type: string example: OK data: description: Present on success. Shape varies per endpoint. error: $ref: '#/components/schemas/GatewayErrorBody' GatewayErrorBody: type: object description: > Machine-readable error classification. EXACTLY ONE of terminal/retriable/ ambiguous is true. laces_api inferred this from the HTTP status and got it wrong, stranding real money twice (2026-08-15, 2026-08-16). Branch on these booleans, never on the status code: terminal -> the provider refused. Reverse the debit and tell the user. retriable -> safe to retry with the SAME Idempotency-Key. ambiguous -> the outcome is UNKNOWN. Do NOT reverse. Poll instead. required: - code - message - terminal - retriable - ambiguous properties: code: type: string description: Stable machine code. Branch on this, never on `message`. example: payout_rejected_by_provider message: type: string description: > Human text from a compiled-in map. NEVER provider text — a stringified provider error can carry an Authorization header. terminal: type: boolean retriable: type: boolean ambiguous: type: boolean details: type: object additionalProperties: type: string responses: BadRequest: description: Validation failed. content: application/json: schema: $ref: '#/components/schemas/APIResult' Unauthorized: description: > Missing, malformed, stale, replayed or invalid signature. Also returned when a body was sent but its raw bytes were unavailable — verified-as-empty must never mean processed-as-full. content: application/json: schema: $ref: '#/components/schemas/APIResult' securitySchemes: AptaPaySignature: type: apiKey in: header name: X-AptaPay-Signature description: > `v1={hex HMAC-SHA256}` over the ten-field canonical string. Sent alongside `X-AptaPay-Key`, `X-AptaPay-Timestamp` and `X-AptaPay-Nonce` — all four are required. OpenAPI can only model one header per scheme, so the other three are described in the Authentication section above. ````