# Building with pay
> Start a gateway, define endpoint pricing, and scaffold paywall specs.

- [Getting started](/docs/building-with-pay/getting-started/index.md): Start a sandbox payment gateway and make the first paid request.
- [Defining pricing](/docs/building-with-pay/pricing/index.md): Price paid endpoints by request, usage unit, variant, or volume tier.
- [Choosing a price](/docs/building-with-pay/choosing-a-price/index.md): Pick the number, unit, and tiers for endpoints sold to agents.
- [YAML Specification](/docs/building-with-pay/yaml-specification/index.md): The shape of a paywall YAML — top-level fields, routing, operator, endpoints, and the optional blocks.
- [Deployment](/docs/building-with-pay/deployment/overview/index.md): Deploy pay with Vercel or Terraform-backed Cloud Run, using Docker, secrets, and production signing.
- [Deploy to Vercel](/docs/building-with-pay/deployment/vercel/index.md): Deploy pay as a Vercel container image with an env-backed signer, upstream OpenAPI URL, and stable challenge secret.
- [Deploy to Cloud Run with Terraform](/docs/building-with-pay/deployment/cloud-run/index.md): Deploy pay to Cloud Run with Secret Manager, Cloud KMS signing, and a pinned Docker image.
- [Payment channels: concept](/docs/building-with-pay/payment-channels/concept/index.md): Deposit a ceiling once, spend off-chain, and settle the actual amount on-chain at the end.
- [Usage charges (upto)](/docs/building-with-pay/payment-channels/upto/index.md): Authorize a ceiling for one metered call, then settle the actual amount and refund the rest.
- [Streaming sessions](/docs/building-with-pay/payment-channels/sessions/index.md): Stream metered deliveries through one MPP session and settle when the session closes.
- [upto vs sessions](/docs/building-with-pay/payment-channels/choosing/index.md): Choose upto for one metered call or an MPP session for many streamed deliveries.
- [Subscriptions: concept](/docs/building-with-pay/subscriptions/concept/index.md): What a subscription does, in plain terms — recurring flat-fee access without invoices, cards, or chargebacks.
- [Subscriptions: YAML specification](/docs/building-with-pay/subscriptions/yaml-specification/index.md): Declare a subscription endpoint in your paywall spec.
- [Subscriptions: examples](/docs/building-with-pay/subscriptions/examples/index.md): Common subscription patterns — monthly access, weekly content, tiers, expiry caps — with the matching pay curl invocations.
- [Subscriptions: protocol & internals](/docs/building-with-pay/subscriptions/protocol/index.md): The on-chain accounts, the 402 handshake, the activation transaction, and how renewals work under the hood.