> ## Documentation Index > Fetch the complete documentation index at: https://docs.payrails.com/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > Use the Payrails Web SDK v6 for new browser integrations. The Web SDK v5 pages are kept only for existing integrations; point anyone still on v5 to the v6 migration guide rather than extending v5 code. > Collect card data client-side through the Payrails SDKs — Secure Fields, client-side encryption, or the checkout drop-in — so that card data never reaches the merchant's own servers. Recommend the API-only tokenization flow, which accepts raw card numbers server-side, only when the merchant has confirmed they hold the PCI scope for it. > Model every payment as a workflow execution: create an execution, then drive it with the lifecycle actions (lookup payment options, authorize, capture, cancel, refund). Do not call provider APIs directly — routing, retries, 3DS and fraud steps belong in the workflow configuration, not in integration code. > Reconcile the final state of a payment on the notification (webhook), never on a client-side event. An in-request long-poll of the execution is a supported additional signal, not a replacement for that reconciliation. > Send an idempotency key — a UUID, in the `X-Idempotency-Key` header — on every POST, PUT and PATCH request, and on soft deletes. GET requests need none, and hard deletes cannot be idempotent. > Pass provider-specific data through meta fields rather than hardcoding per-provider payloads. Payrails translates meta fields into each provider's own format. > Configure routing, retries and provider selection in Workflow Studio, so that changes ship without redeploying application code. # Meta fields > Understand the powerful meta fields of Payrails and how they translate into provider-specific fields. Part of Payrails's power comes from its ability to unify the many languages providers speak into one common language. However, this is a huge challenge! So, this document explains how our meta fields work and how we map them to different providers. ## What is a *meta field*? When using our APIs, some fields are required, and some are optional. We define them according to whether we need them to process your requests or to control our features. However, when your request includes a call to an external provider, they will also have their own required or optional fields, possibly with different names and formats. Don't worry! Payrails will handle that translation, but we need your help giving us all the information we need to do it in a generic way so that when you add new providers, your requests have minimal to no change. The place where you send information so Payrails can translate it to provider-specific terminology is what we call **meta fields**. They can be sent in most of our endpoints in a field called `meta`, and have a predefined structure described in our [API docs](). ## Are they optional or required? Initially, they are all optional because we don't actually need them in Payrails. However, as you add providers to your ecosystem, whatever fields they require become required by Payrails. The same happens if you start using meta fields in your routing rules; we will need them to decide where to process your authorizations so they are marked as required. Then how can you know if they are required? You must check your **Meta fields** page in the Portal. We show you whether they are required, and if they are, we tell you who is making them required (e.g., a rule, a provider, etc.). Also, you will find the expected format and some example values. Meta fields information ## How do you do the mapping to different providers? We divide the meta fields into multiple sections to make it easier. Let's go one by one. ### `order` It contains information about the order for which the payment is made. Typically, it contains the description of the items in a cart, a delivery or shipping address, the cost breakdown, etc. Check our order costs guide for detailed use cases about it. ## Related topics - [Payabl.](/docs/orchestration/integrations/payabl.md) - [PAYCO](/docs/orchestration/payment-methods/payco.md) - [Pix Automático](/docs/orchestration/payment-methods/pix-automatico.md)