> ## Documentation Index > Fetch the complete documentation index at: https://docs.jenzy.com/llms.txt > Use this file to discover all available pages before exploring further. # Simulate a pay-in (sandbox only) > Fund your sandbox balance by pretending a customer paid you. Sandbox only — in production this returns `403 sandbox_only`, because real money can only arrive by being sent to your account number. The simulated pay-in is a real pay-in in every way that matters to your integration: it becomes an ordinary collection, it credits your balance net of the fee, and it fires the `collection.settled` webhook. Nothing marks it as simulated, so the code you write against it is the code that runs in production. **This request is not idempotent.** A `202` means the pay-in exists at the provider but has not credited yet — poll `GET /collections` rather than sending it again, or you will create a second pay-in. Only `4xx` and `503` mean nothing was created. Otherwise, repeat it as often as you like — each call is an independent collection. ## OpenAPI ````yaml /openapi.json post /collections/simulate openapi: 3.1.0 info: title: Jenzy Hermes Client API version: 1.0.0 description: >- Draw down your prefunded MWK balance as payouts to Malawian banks and mobile money. Authenticate with your `jz_live_…` API key as a bearer token. servers: - url: https://api.jenzy.com/v1 description: Production security: [] paths: /collections/simulate: post: summary: Simulate a pay-in (sandbox only) description: >- Fund your sandbox balance by pretending a customer paid you. Sandbox only — in production this returns `403 sandbox_only`, because real money can only arrive by being sent to your account number. The simulated pay-in is a real pay-in in every way that matters to your integration: it becomes an ordinary collection, it credits your balance net of the fee, and it fires the `collection.settled` webhook. Nothing marks it as simulated, so the code you write against it is the code that runs in production. **This request is not idempotent.** A `202` means the pay-in exists at the provider but has not credited yet — poll `GET /collections` rather than sending it again, or you will create a second pay-in. Only `4xx` and `503` mean nothing was created. Otherwise, repeat it as often as you like — each call is an independent collection. requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/SimulatedPayInCreate' responses: '201': description: The collection your simulated pay-in became — already credited. content: application/json: schema: $ref: '#/components/schemas/Collection' '202': description: >- Created at the provider, not yet credited. Poll `GET /collections`; do not retry. content: application/json: schema: $ref: '#/components/schemas/SimulatedPayInPending' '400': description: >- The body is malformed, the amount is not positive or is too large, or the provider refused it. Nothing was created. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '401': description: Missing, malformed, or revoked API key. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '403': description: >- This is a sandbox-only endpoint and this is not the sandbox, or your org has no provider sub-account linked yet. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '503': description: >- Nothing was created and the request is safe to retry. `service_incident` / `service_maintenance` mean the API shutter is closed and the whole `/v1` surface is paused. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' security: - ApiKeyAuth: [] components: schemas: SimulatedPayInCreate: type: object properties: amount_mwk: anyOf: - type: number - type: string description: >- What the pretend sender pays IN — the gross, before fees. You are credited less: the fee comes out of it, exactly as it does on a real pay-in. Either a JSON integer of whole kwacha or an exact decimal string with up to 2 decimal places (`"1000.55"`). Must be positive and no greater than 5000000000 MWK. example: 50000 rail: type: string enum: - momo - bank description: >- Where the pretend sender pays from. Decides the `rail` and `source_institution` on the resulting collection; it does not change the price, which is the same on both. Defaults to `momo`. example: momo required: - amount_mwk Collection: type: object properties: id: type: string format: uuid description: Collection id — your handle for polling and support. status: type: string enum: - settled - reversed description: >- `settled` means the money credited your balance. `reversed` means the provider then clawed the pay-in back — treat the `collection.reversed` event as authoritative; your balance catches up. example: settled amount_mwk: type: string description: >- The gross amount the sender sent — exact decimal string at 2 decimal places. Parse with a decimal library, never a float. example: '1000.00' fee: type: string description: >- The transaction fee, as one combined figure — an exact decimal string. Always equal to `amount_mwk` minus `amount_credited`. Use `POST /fees/quote` to know it in advance. example: '15.00' amount_credited: type: string description: >- What your balance moved by: `amount_mwk` minus `fee`, as an exact decimal string. example: '985.00' rail: type: - string - 'null' enum: - bank - momo - null description: >- How the money arrived: `momo` from a mobile wallet, `bank` from a bank account. Null when the rail could not be determined. source_customer_name: type: - string - 'null' description: Who sent the money, as reported by the provider. example: PETER BANDA source_account_number: type: - string - 'null' description: >- The account or wallet the money came from, verbatim — your handle for matching the pay-in to your own customer. example: '265991234567' source_institution: type: - string - 'null' description: The institution the money came from, as reported by the provider. example: Airtel Money rtp_reference_number: type: - string - 'null' description: >- The reference you supplied when requesting this payment, echoed back for matching. Null when the payer sent the money directly. created_at: type: string format: date-time required: - id - status - amount_mwk - fee - amount_credited - rail - source_customer_name - source_account_number - source_institution - rtp_reference_number - created_at SimulatedPayInPending: type: object properties: status: type: string enum: - pending description: >- The pay-in was created at the provider but has not credited yet. **Do not send this request again** — it is not idempotent, and a second call creates a second pay-in. Poll `GET /collections`; it will appear there, usually within a minute. required: - status ErrorEnvelope: type: object properties: error: type: object properties: code: type: string enum: - validation_error - unauthorized - forbidden - not_found - conflict - rate_limited - internal_error - unknown_institution - invalid_mobile_number - invalid_account_number - mobile_number_institution_mismatch - service_unavailable - sandbox_only - insufficient_funds - rail_disabled - amount_limit_exceeded - org_limit_exceeded - service_incident - service_maintenance description: >- Stable identifier a client may branch on — never renamed or removed. message: type: string required: - code - message required: - error securitySchemes: ApiKeyAuth: type: http scheme: bearer description: 'Your Jenzy API key: `Authorization: Bearer jz_live_…`' ````