These are observations, not accusations. A band of LOW, MEDIUM or HIGH describes how much of what we check we were able to confirm — it is not a judgement about the operator of an endpoint. Every signal, its weight and its rationale are published on the methodology page, and any operator can claim an endpoint, correct a fact or opt out.

What does this x402 endpoint charge?

0.003000 USDC per request

https://2s.io/api/inflation/calculator

LOW 100/100

Observed 2026-08-15T14:31:59Z · 62 ms · HTTP 402 · v1 methodology

WIRE_FORMS_DISAGREEBoth wire forms were served and they describe different terms.

Endpoint

What we observed about the endpoint
URL	https://2s.io/api/inflation/calculator
Canonical	https://2s.io/api/inflation/calculator
Endpoint id	beb1e0e43ef22af3b709556f16db7db2
HTTP status	402
Latency	62 ms
Redirects	0
TLS	handshake okThe negotiated TLS version is not exposed to a Worker.
Wire form	both the v2 header and a v1 body
Bytes read	3812
Strict decoder	accepteddecodePaymentRequired, imported from tx402 — the same code the SDK runs before it pays.

Payment

accepted by the decoder

These terms were accepted by the strict decoder tx402 uses before it pays.

The payment terms this endpoint asks for
Price	0.003000 USDC
Amount (atomic)	3000
Scheme	exact
Network	eip155:8453 in manifestRecognized means present in the tx402 signed release manifest. Nothing more is claimed.
Asset	USDC 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 in manifestRecognized means present in the tx402 signed release manifest. Nothing more is claimed.
Pay to	0x2b6D4988Db4723E6908Db86Ab2b8dFBc51FC32C5
Pay to declared dynamic	nox402 v2 has no on-the-wire declaration of a dynamic payTo, so this is usually unobservable.
Authorization window	60s
Resource	https://2s.io/api/inflation/calculator
MIME type	application/json
Description	Adjust a US dollar amount for inflation between two dates ('what is $100 in 1990 worth today?'). Pass amount, from (YYYY-MM-DD or YYYY), and optional to (defaults to the latest CPI month). Uses CPI-U (CPIAUCNS — the same not-seasonally-adjusted all-items index as the official BLS inflation calculator), data back to 1913. Returns the inflation-adjusted amount, cumulative inflation %, annualized rate, and the CPI index values used on each date. Source: BLS CPI via FRED (St. Louis Fed).
Facilitator	not observed

This endpoint offers 2 ways to pay. The card above describes the first, which is the order the server stated its own preference in.

Other accepted ways to pay
Alternative 2	3000 (atomic units) · solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp · exact

Risk

LOW 100/100 · v1 · static_only

A band describes how much of what we check we were able to confirm. It is not a judgement about the operator of an endpoint.

Result: pass 25 The challenge decodes under the strict x402 decoder tx402 uses before paying. challenge_decodes
Result: pass 15 The challenge describes the endpoint that served it. resource_origin_match
Result: pass 12 The amount is a canonical atomic integer. amount_canonical
Result: pass 12 The recipient is a well-formed address for the declared network. pay_to_wellformed
Result: pass 8 The network is in the tx402 signed release manifest. network_recognized
Result: pass 8 The asset is in the tx402 signed release manifest for this network. asset_recognized
Result: skip — The challenge named no facilitator. facilitator_known
Result: pass 6 The payment scheme is one tx402 can route. scheme_known
Result: pass 5 The endpoint was reached over a valid TLS connection. tls_ok
Result: pass 4 The authorization window is within the maximum tx402 will sign for. timeout_sane
Result: pass 3 No redirect downgraded the connection. redirect_scheme_downgrade
Result: pass 3 The endpoint serves the x402 v2 header form. wire_form
Result: pass 2 The amount is within the range we see for x402 endpoints. amount_magnitude_band

Security

nothing failing

A check that could not run reports skip, and a skip is never counted as a pass.

Result: pass wire_form_detected Served as both.
Result: pass base64_strict The strict decoder accepted the header's base64 framing.
Result: pass json_wellformed
Result: pass x402_version_known Declared x402Version 2.
Result: pass accepts_present The challenge offers 2 ways to pay.
Result: pass size_within_limit Read 3812 bytes, within the probe's cap.
Result: pass network_caip2_wellformed network: eip155:8453
Result: pass network_recognized Recognized means present in the tx402 signed release manifest.
Result: pass asset_recognized Recognized means present in the tx402 signed release manifest.
Result: pass amount_atomic_canonical
Result: pass amount_positive
Result: pass pay_to_wellformed
Result: pass max_timeout_sane
Result: pass resource_origin_match
Result: pass scheme_known
Result: skip facilitator_known The challenge named no facilitator.
Result: pass mime_type_wellformed mimeType: application/json
Result: pass extra_wellformed `extra` carries 2 field(s), preserved verbatim.
Result: skip amount_within_observed_range needs our data No prior observations of this endpoint.
Result: skip recipient_matches_observed needs our data No prior observations of this endpoint.

Observed

What the corpus knows about this endpoint
First seen	2026-08-15T04:00:12Z
Last seen	2026-08-15T14:31:59Z
Scans recorded	2
Availability (30d)	not measured yet
Latency p50	not measured yet

Recorded changes to this endpoint's terms
2026-08-15T06:00:23Z	first_seen: challenge_hash — → 3276b423b3486c9b69c8268ee6d3e24174a640327463122b24eb1e9a8097d9db

Test with tx402 →

Pre-filled with this endpoint's real terms. Your signer stays in your process — this service never sees a key, never asks for one, and cannot build a payment.

CLI — dry run, nothing is signed

npx tx402 call "https://2s.io/api/inflation/calculator" \
  --max-spend "0.003000 USDC" \
  --network "eip155:8453" \
  --dry-run

# --dry-run stops after the policy decision. Nothing is signed and nothing is spent.

TypeScript

import { createTx402Client } from "tx402";
// Your signer stays in your process. tools.tx402.io never sees a key,
// never asks for one, and cannot build a payment.
import { signers } from "./signers.js";

const tx402 = createTx402Client({
  signers,
  policy: {
    maxPerRequest: "0.003000 USDC",
    allowedDomains: ["2s.io"],
    allowedNetworks: ["eip155:8453"],
  },
});

// Policy and budget are committed before the signer is reachable, so a
// refusal here is a payment that was never authorized.
const response = await tx402.fetch("https://2s.io/api/inflation/calculator");

Python

from tx402 import Tx402Client, Policy

# Your signer stays in your process. tools.tx402.io never sees a key,
# never asks for one, and cannot build a payment.
tx402 = Tx402Client(
    evm_signer=evm,
    policy=Policy(
        max_per_request="0.003000 USDC",
        allowed_domains=["2s.io"],
        allowed_networks=["eip155:8453"],
    ),
)

# Policy and budget are committed before the signer is reachable, so a
# refusal here is a payment that was never authorized.
response = tx402.fetch("https://2s.io/api/inflation/calculator")

This report, as JSON or Markdown

curl -sS 'https://tools.tx402.io/api/v1/inspect?url=https%3A%2F%2F2s.io%2Fapi%2Finflation%2Fcalculator'

# The same result as Markdown, for a terminal or an agent:
curl -sS -H 'Accept: text/markdown' 'https://tools.tx402.io/inspect?url=https%3A%2F%2F2s.io%2Fapi%2Finflation%2Fcalculator'

The challenge, as served

Public data: the endpoint serves this to anyone who asks. It is shown exactly as it arrived, truncated to the documented cap.

raw challenge

eyJ4NDAyVmVyc2lvbiI6MiwiYWNjZXB0cyI6W3sic2NoZW1lIjoiZXhhY3QiLCJuZXR3b3JrIjoiZWlwMTU1Ojg0NTMiLCJhbW91bnQiOiIzMDAwIiwiYXNzZXQiOiIweDgzMzU4OWZDRDZlRGI2RTA4ZjRjN0MzMkQ0ZjcxYjU0YmRBMDI5MTMiLCJwYXlUbyI6IjB4MmI2RDQ5ODhEYjQ3MjNFNjkwOERiODZBYjJiOGRGQmM1MUZDMzJDNSIsIm1heFRpbWVvdXRTZWNvbmRzIjo2MCwiZXh0cmEiOnsibmFtZSI6IlVTRCBDb2luIiwidmVyc2lvbiI6IjIifX0seyJzY2hlbWUiOiJleGFjdCIsIm5ldHdvcmsiOiJzb2xhbmE6NWV5a3Q0VXNGdjhQOE5KZFRSRXBZMXZ6cUtxWkt2ZHAiLCJhbW91bnQiOiIzMDAwIiwiYXNzZXQiOiJFUGpGV2RkNUF1ZnFTU3FlTTJxTjF4enliYXBDOEc0d0VHR2tad3lURHQxdiIsInBheVRvIjoiVFc2bnRhR3p2ajYzWmdQanN6ZDRGQ0dtVlRHZnp2MU1BWVpialljeVdobiIsIm1heFRpbWVvdXRTZWNvbmRzIjo2MCwiZXh0cmEiOnsibmFtZSI6IlVTREMiLCJ2ZXJzaW9uIjoiMSIsImZlZVBheWVyIjoiR1ZKSjdyZEdpWHI1eGFZYlJ3UmJqZmFKTDdmbXdSeWdGaTFINmFHcUR2ZWIifX1dLCJyZXNvdXJjZSI6eyJ1cmwiOiJodHRwczovLzJzLmlvL2FwaS9pbmZsYXRpb24vY2FsY3VsYXRvciIsImRlc2NyaXB0aW9uIjoiQWRqdXN0IGEgVVMgZG9sbGFyIGFtb3VudCBmb3IgaW5mbGF0aW9uIGJldHdlZW4gdHdvIGRhdGVzICgnd2hhdCBpcyAkMTAwIGluIDE5OTAgd29ydGggdG9kYXk/JykuIFBhc3MgYW1vdW50LCBmcm9tIChZWVlZLU1NLUREIG9yIFlZWVkpLCBhbmQgb3B0aW9uYWwgdG8gKGRlZmF1bHRzIHRvIHRoZSBsYXRlc3QgQ1BJIG1vbnRoKS4gVXNlcyBDUEktVSAoQ1BJQVVDTlMg4oCUIHRoZSBzYW1lIG5vdC1zZWFzb25hbGx5LWFkanVzdGVkIGFsbC1pdGVtcyBpbmRleCBhcyB0aGUgb2ZmaWNpYWwgQkxTIGluZmxhdGlvbiBjYWxjdWxhdG9yKSwgZGF0YSBiYWNrIHRvIDE5MTMuIFJldHVybnMgdGhlIGluZmxhdGlvbi1hZGp1c3RlZCBhbW91bnQsIGN1bXVsYXRpdmUgaW5mbGF0aW9uICUsIGFubnVhbGl6ZWQgcmF0ZSwgYW5kIHRoZSBDUEkgaW5kZXggdmFsdWVzIHVzZWQgb24gZWFjaCBkYXRlLiBTb3VyY2U6IEJMUyBDUEkgdmlhIEZSRUQgKFN0LiBMb3VpcyBGZWQpLiIsIm1pbWVUeXBlIjoiYXBwbGljYXRpb24vanNvbiIsInNlcnZpY2VOYW1lIjoiMnMiLCJpY29uVXJsIjoiaHR0cHM6Ly8ycy5pby9pY29uLTUxMi5wbmciLCJ0YWdzIjpbInB1YmxpYy1yZWNvcmRzIiwiaWRlbnRpZmllcnMiLCJhaS1hZ2VudHMiLCJ1cy1nb3YtZGF0YSIsIng0MDIiLCJ1cHRvLWJpbGxpbmciLCJhaS1nYXRld2F5IiwiYWdlbnQtaW5mcmFzdHJ1Y3R1cmUiXX0sImVycm9yIjoiUEFZTUVOVC1TSUdOQVRVUkUgcmVxdWlyZWQiLCJleHRlbnNpb25zIjp7ImJhemFhciI6eyJpbmZvIjp7ImlucHV0Ijp7InR5cGUiOiJodHRwIiwibWV0aG9kIjoiR0VUIiwicXVlcnlQYXJhbXMiOnsiYW1vdW50IjoxMDAsImZyb20iOiIxOTkwLTAxLTAxIn19fSwic2NoZW1hIjp7IiRzY2hlbWEiOiJodHRwczovL2pzb24tc2NoZW1hLm9yZy9kcmFmdC8yMDIwLTEyL3NjaGVtYSIsInR5cGUiOiJvYmplY3QiLCJwcm9wZXJ0aWVzIjp7ImlucHV0Ijp7InR5cGUiOiJvYmplY3QiLCJwcm9wZXJ0aWVzIjp7InR5cGUiOnsiY29uc3QiOiJodHRwIn0sIm1ldGhvZCI6eyJjb25zdCI6IkdFVCJ9LCJxdWVyeVBhcmFtcyI6eyJwcm9wZXJ0aWVzIjp7ImFtb3VudCI6eyJ0eXBlIjoibnVtYmVyIiwiZGVzY3JpcHRpb24iOiJEb2xsYXIgYW1vdW50IHRvIGFkanVzdC4ifSwiZnJvbSI6eyJ0eXBlIjoic3RyaW5nIiwiZGVzY3JpcHRpb24iOiJTdGFydCBkYXRlIChZWVlZLU1NLUREIG9yIFlZWVkpLiJ9LCJ0byI6eyJ0eXBlIjoic3RyaW5nIiwiZGVzY3JpcHRpb24iOiJFbmQgZGF0ZSAoWVlZWS1NTS1ERCBvciBZWVlZKS4gRGVmYXVsdHMgdG8gbGF0ZXN0IENQSS4ifX0sInJlcXVpcmVkIjpbImFtb3VudCIsImZyb20iXX19LCJyZXF1aXJlZCI6WyJ0eXBlIiwibWV0aG9kIiwicXVlcnlQYXJhbXMiXX19LCJyZXF1aXJlZCI6WyJpbnB1dCJdfX19fQ==

SHA-256 of the canonicalized challenge: 742a33a6789fdaba0248d3b16b9b4a18d0bb94fe2820a6b4b5b08f21e158ee69

Raw signals

The exact input the scoring function was given. A signal we could not determine has observed: false and contributes nothing to the score — it is never counted as a failure.

signals

[
  {
    "id": "probe_ok",
    "value": true,
    "observed": true,
    "detail": null
  },
  {
    "id": "challenge_served",
    "value": true,
    "observed": true,
    "detail": null
  },
  {
    "id": "challenge_decodes",
    "value": true,
    "observed": true,
    "detail": null
  },
  {
    "id": "wire_form",
    "value": "both",
    "observed": true,
    "detail": null
  },
  {
    "id": "x402_version",
    "value": 2,
    "observed": true,
    "detail": null
  },
  {
    "id": "tls_ok",
    "value": true,
    "observed": true,
    "detail": null
  },
  {
    "id": "tls_protocol",
    "value": null,
    "observed": false,
    "detail": "The negotiated TLS version is not exposed to the probe."
  },
  {
    "id": "redirect_count",
    "value": 0,
    "observed": true,
    "detail": null
  },
  {
    "id": "redirect_scheme_downgrade",
    "value": false,
    "observed": true,
    "detail": "Cross-scheme redirects are refused."
  },
  {
    "id": "resource_origin_match",
    "value": true,
    "observed": true,
    "detail": null
  },
  {
    "id": "network_recognized",
    "value": true,
    "observed": true,
    "detail": "Recognized means present in the tx402 signed release manifest."
  },
  {
    "id": "asset_recognized",
    "value": true,
    "observed": true,
    "detail": "Recognized means present in the tx402 signed release manifest."
  },
  {
    "id": "facilitator_known",
    "value": null,
    "observed": false,
    "detail": "The challenge named no facilitator."
  },
  {
    "id": "amount_canonical",
    "value": true,
    "observed": true,
    "detail": null
  },
  {
    "id": "amount_magnitude_band",
    "value": "micro",
    "observed": true,
    "detail": null
  },
  {
    "id": "pay_to_wellformed",
    "value": true,
    "observed": true,
    "detail": null
  },
  {
    "id": "pay_to_declared_dynamic",
    "value": false,
    "observed": true,
    "detail": null
  },
  {
    "id": "timeout_sane",
    "value": true,
    "observed": true,
    "detail": null
  },
  {
    "id": "scheme_known",
    "value": true,
    "observed": true,
    "detail": null
  },
  {
    "id": "requirement_count",
    "value": 2,
    "observed": true,
    "detail": null
  },
  {
    "id": "challenge_size_bytes",
    "value": 3812,
    "observed": true,
    "detail": null
  },
  {
    "id": "first_seen_age_days",
    "value": null,
    "observed": false,
    "detail": "No history yet."
  },
  {
    "id": "scan_count",
    "value": null,
    "observed": false,
    "detail": "No history yet."
  },
  {
    "id": "availability_30d",
    "value": null,
    "observed": false,
    "detail": "No history yet."
  },
  {
    "id": "latency_p50_ms",
    "value": null,
    "observed": false,
    "detail": "No history yet."
  },
  {
    "id": "price_changes_90d",
    "value": null,
    "observed": false,
    "detail": "No history yet."
  },
  {
    "id": "recipient_changes_90d",
    "value": null,
    "observed": false,
    "detail": "No history yet."
  },
  {
    "id": "recipient_unstable_undeclared",
    "value": null,
    "observed": false,
    "detail": "No history yet."
  },
  {
    "id": "terms_changed_within_24h",
    "value": null,
    "observed": false,
    "detail": "No history yet."
  }
]

JSON Markdown Methodology Error reference