---
title: "POST /transactions"
method: POST
path: "/transactions"
tags: ["Transactions"]
---

# POST /transactions

`POST /transactions`

Syncs a transaction, optionally with allocations

## Request body

- SyncTransactionRequest — Sync an unreconciled transaction.
  - `external_id` string, required — External transaction ID used for idempotent sync.
  - `account` TransactionAccountReferenceInput, required — Account reference. Provide id, external_id, or both.
    - `id` string — User-facing encoded account ID.
    - `external_id` string — External account reference ID.
  - `posted` string, date-time, required — Posted timestamp in ISO 8601 format.
  - `currency` 'ADA' | 'BTC' | 'DAI' | 'ETH' | 'SOL' | 'USDC' | 'USDT' | 'USDG' | 'EURC' | 'CADC' | 'CADT' | 'XLM' | 'UNI' | 'BCH' | 'LTC' | 'AAVE' | 'LINK' | 'MATIC' | 'PTS' | 'AED' | 'AFN' | 'ALL' | 'AMD' | 'ANG' | 'AOA' | 'ARS' | 'AUD' | 'AWG' | 'AZN' | 'BAM' | 'BBD' | 'BDT' | 'BGN' | 'BHD' | 'BIF' | 'BMD' | 'BND' | 'BOB' | 'BRL' | 'BSD' | 'BTN' | 'BWP' | 'BYR' | 'BZD' | 'CAD' | 'CDF' | 'CHF' | 'CLP' | 'CNY' | 'COP' | 'CRC' | 'CUC' | 'CUP' | 'CVE' | 'CZK' | 'DJF' | 'DKK' | 'DOP' | 'DZD' | 'EGP' | 'ERN' | 'ETB' | 'EUR' | 'FJD' | 'FKP' | 'GBP' | 'GEL' | 'GGP' | 'GHS' | 'GIP' | 'GMD' | 'GNF' | 'GTQ' | 'GYD' | 'HKD' | 'HNL' | 'HRK' | 'HTG' | 'HUF' | 'IDR' | 'ILS' | 'IMP' | 'INR' | 'IQD' | 'IRR' | 'ISK' | 'JMD' | 'JOD' | 'JPY' | 'KES' | 'KGS' | 'KHR' | 'KMF' | 'KPW' | 'KRW' | 'KWD' | 'KYD' | 'KZT' | 'LAK' | 'LBP' | 'LKR' | 'LRD' | 'LSL' | 'LYD' | 'MAD' | 'MDL' | 'MGA' | 'MKD' | 'MMK' | 'MNT' | 'MOP' | 'MUR' | 'MVR' | 'MWK' | 'MXN' | 'MYR' | 'MZN' | 'NAD' | 'NGN' | 'NIO' | 'NOK' | 'NPR' | 'NZD' | 'OMR' | 'PAB' | 'PEN' | 'PGK' | 'PHP' | 'PKR' | 'PLN' | 'PYG' | 'QAR' | 'RON' | 'RSD' | 'RUB' | 'RWF' | 'SAR' | 'SBD' | 'SCR' | 'SDG' | 'SEK' | 'SGD' | 'SHP' | 'SLL' | 'SOS' | 'SPL' | 'SRD' | 'SVC' | 'SYP' | 'STN' | 'SZL' | 'THB' | 'TJS' | 'TMT' | 'TND' | 'TOP' | 'TRY' | 'TTD' | 'TVD' | 'TWD' | 'TZS' | 'UAH' | 'UGX' | 'USD' | 'UYU' | 'UZS' | 'VEF' | 'VND' | 'VUV' | 'WST' | 'XAF' | 'XCD' | 'XOF' | 'XPF' | 'YER' | 'ZAR' | 'ZMW' | 'LOGICAL' | 'CUSTOM', required — Currency code (ISO 4217 or crypto)
  - `amount` string, required — Amount in smallest currency unit as stringified bigint (can be positive or negative).
  - `allocations` TransactionAllocation[], required — Allocation entries for this transaction. Empty indicates unreconciled funds.
    - `invoice_id` string, required — The invoice to allocate against.
    - `amount` string, required — Amount to allocate in smallest currency unit as stringified bigint.
    - `type` 'invoice_payin' | 'invoice_payout', required — The type of allocation.
    - `user` union, required
      - object
        - `id` string, required — FRAGMENT generated ID of the user
      - object
        - `external_id` string, required — External ID of the user
  - `tags` TagRequest[] — Optional metadata tags for this transaction
    - `key` string, required — Tag key. Must be a valid safe string (no special characters like #, /, :). Max 50 characters.
    - `value` string, required — Tag value. Must be a valid safe string (no special characters like #, /, :). Max 200 characters.

## Response `201`

Success

- TransactionSuccessResponse
  - `data` Transaction, required — Transaction object.
    - `id` string, required — User-facing encoded transaction ID.
    - `external_id` string, required — External idempotency key provided by the user.
    - `account` TransactionAccountReference, required
      - `id` string, required — User-facing encoded account ID.
      - `external_id` string, required — External account reference ID.
    - `posted` string, date-time, required — Posted timestamp in ISO 8601 format.
    - `currency` 'ADA' | 'BTC' | 'DAI' | 'ETH' | 'SOL' | 'USDC' | 'USDT' | 'USDG' | 'EURC' | 'CADC' | 'CADT' | 'XLM' | 'UNI' | 'BCH' | 'LTC' | 'AAVE' | 'LINK' | 'MATIC' | 'PTS' | 'AED' | 'AFN' | 'ALL' | 'AMD' | 'ANG' | 'AOA' | 'ARS' | 'AUD' | 'AWG' | 'AZN' | 'BAM' | 'BBD' | 'BDT' | 'BGN' | 'BHD' | 'BIF' | 'BMD' | 'BND' | 'BOB' | 'BRL' | 'BSD' | 'BTN' | 'BWP' | 'BYR' | 'BZD' | 'CAD' | 'CDF' | 'CHF' | 'CLP' | 'CNY' | 'COP' | 'CRC' | 'CUC' | 'CUP' | 'CVE' | 'CZK' | 'DJF' | 'DKK' | 'DOP' | 'DZD' | 'EGP' | 'ERN' | 'ETB' | 'EUR' | 'FJD' | 'FKP' | 'GBP' | 'GEL' | 'GGP' | 'GHS' | 'GIP' | 'GMD' | 'GNF' | 'GTQ' | 'GYD' | 'HKD' | 'HNL' | 'HRK' | 'HTG' | 'HUF' | 'IDR' | 'ILS' | 'IMP' | 'INR' | 'IQD' | 'IRR' | 'ISK' | 'JMD' | 'JOD' | 'JPY' | 'KES' | 'KGS' | 'KHR' | 'KMF' | 'KPW' | 'KRW' | 'KWD' | 'KYD' | 'KZT' | 'LAK' | 'LBP' | 'LKR' | 'LRD' | 'LSL' | 'LYD' | 'MAD' | 'MDL' | 'MGA' | 'MKD' | 'MMK' | 'MNT' | 'MOP' | 'MUR' | 'MVR' | 'MWK' | 'MXN' | 'MYR' | 'MZN' | 'NAD' | 'NGN' | 'NIO' | 'NOK' | 'NPR' | 'NZD' | 'OMR' | 'PAB' | 'PEN' | 'PGK' | 'PHP' | 'PKR' | 'PLN' | 'PYG' | 'QAR' | 'RON' | 'RSD' | 'RUB' | 'RWF' | 'SAR' | 'SBD' | 'SCR' | 'SDG' | 'SEK' | 'SGD' | 'SHP' | 'SLL' | 'SOS' | 'SPL' | 'SRD' | 'SVC' | 'SYP' | 'STN' | 'SZL' | 'THB' | 'TJS' | 'TMT' | 'TND' | 'TOP' | 'TRY' | 'TTD' | 'TVD' | 'TWD' | 'TZS' | 'UAH' | 'UGX' | 'USD' | 'UYU' | 'UZS' | 'VEF' | 'VND' | 'VUV' | 'WST' | 'XAF' | 'XCD' | 'XOF' | 'XPF' | 'YER' | 'ZAR' | 'ZMW' | 'LOGICAL' | 'CUSTOM', required — Currency code (ISO 4217 or crypto)
    - `amount` string, required — Amount in smallest currency unit as stringified bigint (can be positive or negative).
    - `allocations` TransactionAllocationResponse[], required
      - `invoice_id` string, required — The invoice to allocate against.
      - `amount` string, required — Amount to allocate in smallest currency unit as stringified bigint.
      - `type` 'invoice_payin' | 'invoice_payout', required — The type of allocation.
      - `user` UserOutput, required
        - `id` string, required — FRAGMENT generated ID of the user
        - `external_id` string — External ID of the user
    - `tags` Tag[], required — Metadata tags associated with this transaction.
      - `key` string, required — Tag key
      - `value` string, required — Tag value
    - `unallocated_amount` string, required — Read-only amount not yet allocated.
    - `created` string, date-time, required — Creation timestamp.
    - `modified` string, date-time — Last modified timestamp.
    - `version` integer, required — Current version of the transaction, used for optimistic concurrency control.

## Other responses

- `400` — Invalid request
- `401` — Unauthorized
- `500` — Internal server error

## Changes

- **2026-03-18** `249df29a7dfe` — 2 info
  - added the new optional request property `tags`
  - added the required property `data/tags` to the response with the `201` status
- **2026-03-12** `930de445f98d` — 2 breaking, 1 info
  - the `account/external_id` request property's minLength was increased from `0` to `1`
  - the `account/id` request property's minLength was increased from `0` to `1`
  - added the optional property `data/allocations/items/user/external_id` to the response with the `201` status
- **2026-03-06** `6768d46dbde8` — 2 breaking, 3 info
  - removed `subschema #1, subschema #2` from the `allocations/items/user` request property `anyOf` list
  - the `data/allocations/items/user` response's property type changed from no type to `object` for status `201`
  - added `subschema #1, subschema #2` to the `allocations/items/user` request property `anyOf` list
  - removed `subschema #1, subschema #2` from the `data/allocations/items/user` response property `anyOf` list for the response status `201`
  - …1 more
- **2026-02-20** `7bc74a705687` — 1 info
  - added the required property `data/version` to the response with the `201` status
- …earlier changes not shown

[Full history](https://skmtc.dev/fragment-dev/apis/fragment-payments-api/changes/transactions/post.md)

---

[API](https://skmtc.dev/fragment-dev/apis/fragment-payments-api.md) · [All operations](https://skmtc.dev/fragment-dev/apis/fragment-payments-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/fragment-dev/fragment-payments-api/revisions/249df29a7dfe/schema)