Pricing and limits

A release test costs 1.00 USDC, paid by you to Selo. Selo pays your endpoint’s price from its own wallet, up to 0.50 USDC per job. Everything else is free.

Who pays what

Payment	Payer	Payee	Amount	When
Release test	You (your payer wallet)	Selo	1.00 USDC	Once per release test, over x402 on `POST /v1/release-test`
Your endpoint’s price	Selo (its own wallet)	Your endpoint’s payTo	Your price, at most 0.50 USDC	Once per release test, after Selo’s own payment has settled
Authorization	none	none	Free	`POST /v1/authorizations` and its verify call
Preflight	none	none	Free	`POST /v1/preflight`
Report, keys, discovery	none	none	Free	`GET /v1/reports/:token`, `/.well-known/…`, `/llms.txt`

The replay in the retry check re-sends the payment Selo already made. It is not a second payment from Selo; a correct endpoint rejects it or returns its stored result without settling again.

Prices and spend caps

These are the values on the public API at https://api.useselo.xyz. They are also the defaults in apps/api/src/env.ts for anyone running Selo themselves.

Limit	Value	Setting	What happens at the limit
Selo’s price	1.00 USDC	`SELO_TEST_PRICE_USDC`	The amount in Selo’s `402` (`"amount": "1000000"` in micro-USDC)
Target price budget per job	0.50 USDC	`SELO_JOB_MAX_SPEND_USDC`	A target priced higher is refused by the preflight with `PRICE_OVER_BUDGET`, and the paid route refuses it with `422 PRICE_OVER_BUDGET` before charging
Absolute cap	5.00 USDC	`SELO_ABSOLUTE_MAX_SPEND_USDC`	No job budget can exceed it. The server refuses to start with a higher value, and a database CHECK constraint enforces it

Before every downstream signature Selo checks:

settled + reserved + unresolved + amount  ≤  job budget  ≤  5.00 USDC

The check is one conditional database update in the same transaction that records the payment, so parallel attempts cannot overspend. An amount whose outcome is unclear stays counted as unresolved and blocks every later reservation. See Payments and spend limits.

Time limits

Limit	Value	Notes
Verification challenge	1 hour	Verify a new `auth create` challenge within an hour, or it expires with `CHALLENGE_EXPIRED`
Authorization	24 hours	Counted from verification (`AUTHORIZATION_TTL_HOURS`). Rechecked before the first probe and before the replay
Preflight	15 minutes	`PREFLIGHT_TTL_MINUTES`. An expired preflight is refused with `409 PREFLIGHT_EXPIRED`. `selo test` runs a fresh one on every run
Job wall clock	60 seconds	`JOB_WALL_CLOCK_MS`. Checks that cannot finish in time end INCONCLUSIVE with `TARGET_TIMEOUT`
Handshake request to your endpoint	10 seconds	The unpaid request that reads your `402`
Paid request and replay	20 seconds each	The paid request to your endpoint and the replay
`selo` CLI request timeout	300 seconds	Per request from the CLI to Selo. A release test waits for settlement and the downstream call
Recovering with `--resume`	15 minutes	`--resume` reuses the same preflight, so it works while that preflight is valid

Size limits

Limit	Value	What happens over the limit
JSON request body to the Selo API	64 KiB	`413 PAYLOAD_TOO_LARGE`
Preflight `requestBody`	16 KiB, serialized	`400 VALIDATION_FAILED`. Allowed only with `POST`, and must not be `null`
`/.well-known/selo-verification.txt`	4,096 bytes	Verification fails with `VERIFICATION_FAILED`
Paid response body Selo reads	256 KiB	`response_contract` is INCONCLUSIVE with `BODY_TOO_LARGE`
CLI `--contract` and `--body` files	64 KiB each	The CLI exits `3` before paying
`targetUrl`	2,048 characters	`400 VALIDATION_FAILED`
`project` / `contact` on an authorization	1–80 / 3–200 characters	`400 VALIDATION_FAILED`
Release id (`--release`, `deploymentId`)	1–128 characters of `A-Z a-z 0-9 . _ -`	The CLI exits `3`; the API answers `400 VALIDATION_FAILED`
`Idempotency-Key` header on the paid route	8–128 characters of `A-Z a-z 0-9 _ -`	`400 VALIDATION_FAILED`

Scope

Item	Supported
Profile	`quick` only: an unpaid read of your `402`, one paid request and one replay
Methods	`GET` and `POST` (JSON body)
Network	Algorand Mainnet, CAIP-2 `algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=`
Asset	USDC, ASA `31566704`, `exact` scheme
Facilitator	GoPlausible, `https://facilitator.goplausible.xyz`
Targets	HTTPS on a public hostname and the default port. Private, loopback, link-local, CGNAT and metadata addresses are refused

A self-hosted Selo can run on Algorand Testnet instead (USDC ASA 10458941), and the CLI accepts --network testnet for it. The public API runs on Mainnet only.

The CLI’s own guard: `--max-usdc`

selo test takes a per-run budget for what you pay Selo. It is checked against the price in Selo’s live 402 before anything is signed.

Rule	Result
Selo’s price is above `--max-usdc`	Refused before signing, exit `3`
Selo’s price is zero or above 5.00 USDC	Refused before signing, exit `3`, whatever `--max-usdc` says
The `402` is on a network other than `--network`	Refused before signing, exit `3`
The `402` names a payee other than `--pay-to`	Refused before signing, exit `3`
`--network mainnet` without `--approve-mainnet` and `--pay-to`	Refused before any request, exit `3`

--max-usdc 1.00 covers today’s price. If Selo’s price ever changes, the run stops before paying and you raise the budget deliberately. See selo test.

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Guides

Concepts

Resources

Pricing and limits

Who pays what

Prices and spend caps

Time limits

Size limits

Scope

The CLI’s own guard: `--max-usdc`

​Who pays what

​Prices and spend caps

​Time limits

​Size limits

​Scope

​The CLI’s own guard: --max-usdc

Who pays what

Prices and spend caps

Time limits

Size limits

Scope

The CLI’s own guard: `--max-usdc`