Deterministic package existence for PyPI and npm, built from real published arti
Deterministic package existence for PyPI and npm, built from real published artifacts (never LLM guesses). Negative answers and typosquat-adjacency flags carry signed proof. $0.002 USDC per check.
Answeringour last check, 2026-09-24
1 of 1checks answered this week
3893 msmedian answer time
$0.002listed price per call
$0.002price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://attester.dev/v1/package/exists
| Category | Everything else |
|---|---|
| Provider host | attester.dev |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 2 from 2 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-09-24 | valid payment request | 402 | $0.002 | 3893 ms |
Example input (from the provider)
{
"body": {
"ecosystem": "pypi",
"name": "requests"
},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"properties": {
"ecosystem": {
"enum": [
"pypi",
"npm"
],
"type": "string"
},
"name": {
"description": "Package name",
"type": "string"
}
},
"required": [
"ecosystem",
"name"
],
"type": "object"
},
"bodyType": {
"enum": [
"json"
],
"type": "string"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"type": "object"
}
},
"required": [
"example"
],
"type": "object"
}
},
"required": [
"input"
]
}