---
title: "TypeScript API surface"
description: "Every value the tx402 core entry point exports, generated from the built package."
source: https://docs.tx402.io/reference/api-typescript/
---

# TypeScript API surface

{/*
  GENERATED FILE — DO NOT EDIT.

  Emitted by `node tools/docs-gen/index.js build` from the shipped source named in each
  section. Edit the source and regenerate; `pnpm docs:check` fails if this file is stale.
*/}

Generated from the built `tx402` package's own exports, so this list cannot claim a symbol the
package does not ship. Signatures and per-symbol documentation live in the bundled `.d.ts`
files, which your editor reads directly — this page answers "what is available and from where".

## `tx402` — the core entry point

Importing this path **must not load a chain library**, and a package-contract test asserts it.
`viem`, `@solana/kit`, `@x402/evm`, and `@x402/svm` are reached through a lazy `import()`
only when a payment on that family is actually planned.

### Functions

- `assertValidReleaseManifest`
- `chainFamily`
- `createBalanceProbeCache`
- `createTx402Client`
- `decodePaymentRequired`
- `digestRequestBody`
- `fingerprintRequest`
- `formatMoneyDecimal`
- `isEvmSigner`
- `isSolanaSigner`
- `isTx402Error`
- `normalizeFingerprintUrl`
- `normalizePolicyHost`
- `orderRouteCandidates`
- `parseMoneyAtomic`
- `parsePositiveMoneyAtomic`
- `planRoutes`
- `requireNetwork`
- `resolveNetwork`
- `verifyReleaseManifest`

### Classes and constructors

- `AmbiguousPaymentError`
- `BudgetExceededError`
- `ClockSkewError`
- `ConfigurationError`
- `DomainNotAllowedError`
- `HealthIndex`
- `InsufficientLiquidityError`
- `InvalidPaymentRequiredError`
- `MemorySpendStore`
- `MoneyParseError`
- `NonReplayableRequestError`
- `PaidRedirectBlockedError`
- `PolicyEngine`
- `RecipientUnpinnedError`
- `ReservedHeaderError`
- `ResourceDeliveryError`
- `SignerError`
- `SpendScopeFrozenError`
- `TransportError`
- `Tx402Error`
- `UnsupportedProtocolError`
- `UnsupportedSchemeError`

### Constants

- `BALANCE_KEY_SEPARATOR`
- `BALANCE_TIMEOUT_MS`
- `BUNDLED_MANIFEST`
- `CIRCUIT_OPEN_MS`
- `EVENT_NAMES`
- `HEALTH_CONSECUTIVE_FAILURES_TO_OPEN`
- `HEALTH_EWMA_ALPHA`
- `HEALTH_FAILURE_RATE_TO_OPEN`
- `HEALTH_FAILURE_WINDOW`
- `HEALTH_IDLE_RETENTION_MS`
- `HEALTH_LATENCY_PENALTY_MAX`
- `HEALTH_LATENCY_REFERENCE_MS`
- `HEALTH_MAX_ENDPOINTS`
- `HEALTH_MIN_SAMPLES_FOR_RATE`
- `HEALTH_NEW_ENDPOINT_SCORE`
- `HEALTH_OPEN_MS`
- `MANIFEST_SIGNING_DOMAIN`
- `MAX_AUTHORIZATION_SECONDS`
- `MAX_PAYMENT_REQUIRED_BYTES`
- `MAX_PAYMENT_REQUIRED_DEPTH`
- `MAX_PAYMENT_REQUIREMENTS`
- `MAX_PROVIDERS_PER_NETWORK`
- `PACKAGE_NAME`
- `PACKAGE_VERSION`
- `PROJECT_URLS`
- `PROTOCOL_HEADERS`
- `REQUEST_FINGERPRINT_DOMAIN`
- `REQUEST_ID_HEADER`
- `RESERVATION_TTL_MS`
- `RESERVED_REQUEST_HEADERS`
- `ROLLING_WINDOW_MS`
- `TRUSTED_MANIFEST_KEYS`
- `TX402_ERROR_CODES`
- `TX402_ERROR_DESCRIPTORS`
- `TX402_ERROR_TAXONOMY`
- `X402_PROTOCOL_VERSION`

## The client itself

`createTx402Client(config)` returns an object carrying these methods. They are read from a
constructed instance, so this list cannot claim a method the package does not ship.

- `inspect(input: Tx402RequestInfo, init?: Tx402RequestInit): Promise<PaymentInspection>`
- `plan(input: Tx402RequestInfo, init?: Tx402RequestInit): Promise<PaymentPlan>`
- `fetch(input: Tx402RequestInfo, init?: Tx402RequestInit): Promise<Response>`
- `getBudgetState(): BudgetState`
- `queryBudgetState(query: BudgetQuery): Promise<BudgetState>`
- `resetHealth(): void`

`fetch` is the one most code calls. The other five are what you reach for when a payment has
to be reasoned about rather than simply made: `plan` answers "what would this cost" without
signing or reserving, `inspect` returns the raw challenge, and `getBudgetState` /
`queryBudgetState` read the spend ledger — the latter for any scope, including one written by
another process. Reconciling a settlement from code starts with `plan` and ends with
`queryBudgetState`.

## Optional subpath exports

| Import | Loads | Use when |
| ------ | ----- | -------- |
| `tx402/evm` | `viem`, `@x402/evm` | You pay on an EVM network and want the bundled adapter. |
| `tx402/solana` | `@solana/kit`, `@x402/svm` | You pay on Solana and want the bundled adapter. |
| `tx402/signers` | `viem/accounts`, and `@solana/kit` lazily | Development only. `privateKeyToEvmSigner` wraps a raw hex key as an `EvmSigner`; `keypairToSolanaSigner` wraps a keypair as a `SolanaSigner`. |

The Python package mirrors this split with extras: `pip install tx402` is the core,
`tx402[evm]`, `tx402[svm]`, and `tx402[all]` add the chain libraries. `import tx402` loads no
chain library in either language.

## More documentation

- Documentation index (Markdown): https://docs.tx402.io/sitemap.md
- Machine index: https://docs.tx402.io/llms.txt · full text: https://docs.tx402.io/llms-full.txt
- This page: https://docs.tx402.io/reference/api-typescript/