# Twikey

> Twikey is a payment platform for recurring billing, mandates, and invoicing. Integration ranges from send-and-forget (submit an invoice, Twikey handles everything) to deeply integrated fine control (manage mandates, transactions, payment links, and dunning yourself). These models coexist — mix and match as needed.

Check use cases if your goal is already described. Read core concepts. Read the implementation guide — it explains when to use which endpoint and how they interact. Decide which integration approach fits best. Check the sequence diagrams for exact endpoint flows. Then read the specific API reference pages for the structures you need. The implementation guide and sequence diagrams complement each other — one has the routing logic, the other has the exact calls.

## Understand how Twikey works

- [Sample use cases](https://www.twikey.com/developers/use-cases.md): Improving your digital invoice pages with Twikey, the automatic payment, the one-off payment
- [Core concepts](https://www.twikey.com/developers/usage-guidelines.md): Sessions, feeds, webhooks vs polling, idempotency keys, error handling
- [Implementation guide](https://www.twikey.com/developers/api-flows.md): Explains when to use which endpoint and how they interact — accepting payments and invoices, payment feed, bulk payments, actions on a payment or invoice, line items, credit notes vs refunds, mandates and tokens, invite vs sign endpoint, customer signing flows, signing via first payment, B2B validation, mandate feed, actions on a mandate, mandate lifecycle, payment links, transactions, transaction feed, bulk transactions, refunding a transaction
- [Sequence diagrams](https://www.twikey.com/developers/sequence-diagrams.md): Exact endpoint flows with actors and preconditions — shows what to call but not when or why (see implementation guide for that). Covers invoices, mandates, payment links, transactions, subscriptions, refunds, identity checks

## API Reference

- [Invoices](https://www.twikey.com/api/invoices.md): Create invoice, update invoice, delete invoice, invoice feed, payment feed, invoice details, action an invoice, bulk create invoices, bulk batch details, credit notes
- [Paymentlinks](https://www.twikey.com/api/paymentlinks.md): Create paymentlink, paymentlink feed, status paymentlink, refund paymentlink, remove paymentlink, metadata
- [Mandate](https://www.twikey.com/api/mandate.md): Invite a customer, sign a mandate, mandate actions, mandate feed, mandate query, cancel agreements, fetch mandate details, update mandate details, customer access, retrieve mandate PDF, upload PDF, retrieve legal terms
- [Transactions](https://www.twikey.com/api/transaction.md): Create transaction, bulk create transactions, bulk batch details, transaction feed, transaction status, action on transaction, update a transaction, refund a transaction
- [Subscriptions](https://www.twikey.com/api/subscriptions.md): Add a subscription, update a subscription, patch a subscription, cancel a subscription, retrieve a single subscription, query all subscriptions, action a subscription
- [Collections](https://www.twikey.com/api/collection.md): Execute collection, status collection, import collection, query collections
- [Refunds (Credit Transfer)](https://www.twikey.com/api/refunds.md): Create a credit transfer, credit transfer feed, details, remove, batch creation, batch details, get beneficiary accounts, add a beneficiary account, disable a beneficiary account
- [Webhooks](https://www.twikey.com/api/callback.md): Contract, payment, bulk, customer, letter, peppol event types, signature validation, retry mechanism, thank you page
- [Testing](https://www.twikey.com/developers/test.md): Transaction outcomes, dunning, wire transfers, B2B mandate acceptance, signing methods, payment links and QR codes, iDEAL 2.0, webhooks, collection agency, letters


## Optional

- [Changes](https://www.twikey.com/api/changelog.md): API changelog
- [Test data](https://www.twikey.com/api/testdata.md): Test data reference
- [Development Kit](https://github.com/twikey/development-kit): All SDKs, OpenAPI spec, Postman collection
- [C#](https://github.com/twikey/twikey-api-dotnet)
- [Java](https://github.com/twikey/twikey-api-java)
- [PHP](https://github.com/twikey/twikey-api-php)
- [Python](https://github.com/twikey/twikey-api-python)
- [Go](https://github.com/twikey/twikey-api-go)
- [Ruby](https://github.com/twikey/twikey-api-ruby)
- [Reconciliation](https://www.twikey.com/api/Reconciliation.md): Generate files, list files, download file
- [Customer](https://www.twikey.com/api/customers.md): Update a customer
- [Issuers](https://www.twikey.com/api/issuers.md): Fetch connected banks
- [Other](https://www.twikey.com/api/misc.md): Rate limits, blacklist account, account reporting, retrieve identification URL, transaction reservations, get payment methods, IBAN-name check, accepted SEPA characters