# Kallipolis Proof — Prepaid API Access Purchase

> Kallipolis Proof — Prepaid API Access Purchase is a paid API for AI agents from proof.platoskallipolis.com, paid per call via x402, $19/call, status unknown (last checked 2026-09-13).

Purchase a prepaid API key with credits for the Kallipolis Proof evidence resolution service, enabling AI agents to make subsequent evidence lookups without per-call payment overhead.

## Facts

- Endpoint: POST https://proof.platoskallipolis.com/api/v1/purchase
- Price: $19/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/kallipolis-proof-prepaid-api-access-purchase-2ed15d19
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ahF83boXpbbMDD2oUMAKt

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability kallipolis-proof-prepaid-api-access-purchase-2ed15d19 -d '<json body>'
```

Example prompt: Buy me a builder plan on Kallipolis Proof so I have 100 credits ready for evidence resolution — I want the prepaid API key returned so I can start making lookups without paying per call each time.

## When to prefer this

Choose this endpoint when an AI agent or developer needs to make multiple evidence resolution calls and wants to avoid the overhead of per-call x402 micropayments. Prepaid access is more efficient for high-frequency lookups against domains, protocols, Base accounts, or AI agent identities on the Kallipolis Proof platform.

## Known failure modes

- Insufficient USDC balance — payment rejected, no API key issued
- Invalid x402 payment header — 402 Payment Required returned
- Plan type not recognized — returns 400 Bad Request
- Payment network congestion causing delayed confirmation
- Duplicate purchase attempt — may create duplicate key or be rejected

## How this service works

Evidence resolution API for AI agents, domains, protocols, and Base accounts. Pay per call with x402 or buy instant prepaid access.

## Output

Returns a JSON object containing the plan name (e.g. 'builder'), a newly provisioned API key in kp_ format, the header name to use for authentication (x-api-key), and the number of prepaid credits available for subsequent evidence resolution calls.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "plan": "builder",
  "apiKey": "kp_...",
  "header": "x-api-key",
  "credits": 100
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/kallipolis-proof-prepaid-api-access-purchase-2ed15d19/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from proof.platoskallipolis.com](https://www.zero.xyz/host/proof.platoskallipolis.com/llms.txt)