# upto vs sessions

> Both are payment channels — pick upto for one metered call, sessions for a stream of many deliveries. The full comparison and when to use which.

Both `upto` and sessions are [payment channels](/docs/building-with-pay/payment-channels/concept): deposit a ceiling, meter off-chain, settle the actual amount, refund the rest. The difference is **how many deliveries one channel meters**.

> **The rule:** one metered call → **`upto`**; a stream of many deliveries → **`session`**.

## Side by side

| Aspect                         | x402 `upto`                                     | MPP `session`                                                  |
| ------------------------------ | ----------------------------------------------- | -------------------------------------------------------------- |
| Protocol                       | x402                                            | MPP                                                            |
| Metered deliveries per channel | one                                             | many (streamed)                                                |
| Buyer authorizes               | a ceiling (signs the channel `open`)            | a running total (signs a cumulative voucher per delivery)      |
| Who signs settlement           | the operator (one voucher)                      | the buyer's vouchers; operator settles at close                |
| Settlement                     | once, after the call                            | once, after the last delivery (idle-close)                     |
| Recipients                     | single `pay_to`                                 | multi-recipient splits (percentage)                            |
| Reuse / top-up                 | no — open once, settle once                     | yes — `topUp`, plus a client force-close escape                |
| Best for                       | one call whose cost is known only after it runs | streaming (SSE) or many cheap calls in one session             |
| CLI config                     | endpoint `schemes: [x402-upto]` (+ `min_usd`)   | top-level `session:` block + endpoint `schemes: [mpp-session]` |

## When to pick `upto`

- A single request whose price you can only compute **after** the work — LLM tokens, per-byte, per-second compute.
- You want the simplest channel: one authorization, one settlement, automatic refund.
- A single recipient is fine (no splits across parties).

See [Usage charges](/docs/building-with-pay/payment-channels/upto).

## When to pick a session

- You're **streaming** — a token-by-token SSE response metered per chunk.
- A client makes **many** cheap calls you'd rather not open a channel for each time.
- You need to **split** the settled total across recipients, or let buyers `topUp` mid-session.

See [Streaming sessions](/docs/building-with-pay/payment-channels/sessions).

## When you need neither

Payment channels earn their keep when the amount is uncertain or metered over time. If the price is **fixed and known up front**, a one-shot charge is simpler:

- **Fixed per-call charge** — [metered pricing](/docs/building-with-pay/pricing) with `mpp-charge` or `x402-exact`: the buyer pays a known amount per request, settled immediately.
- **Recurring flat access** — [subscriptions](/docs/building-with-pay/subscriptions/concept): one signup, recurring charges, free at the point of use within the period.