sigtap - Cold email grader: score an email 0-100 with concrete fixes (subject line, body, spam risk)
https://sigtap-outreach-api.sigtap.workers.dev/gradeOverview
x402 USDC on Base - no signup, the wallet is the account. Free check: GET https://sigtap-outreach-api.sigtap.workers.dev/preview/grade returns a 200 sample. Paid call in 3 steps: GET https://sigtap-outreach-api.sigtap.workers.dev/grade -> 402 challenge (payTo+amount) -> sign and retry with the X-PAYMENT header (@x402/fetch does this) -> 200 + settled on-chain. Catalog + MCP twin: GET /llms.txt on this origin.
Protocol
x402
Price
$0.0050
Payment Asset
USDC
Payment Network
Base
Category
email-marketing
Provider
sigtap
Source
self-registered
Indexed
2026-09-05 12:51:33
Health
Status
healthy
Latency (p50)
799ms
Uptime (30d)
100.0%
Reliability Score
90/100
Last Checked
2026-09-18 09:22:26
Last Healthy
2026-09-18 09:22:26
Consecutive Failures
0
x402 Payment Validation
Payment Requirements
Valid
Asset Verified
Known USDC
Facilitator
—
Recent Health Checks
| Time | Status | HTTP | Latency | Error |
|---|---|---|---|---|
| 2026-09-18 09:22:26 | healthy | 402 | 6042ms | |
| 2026-09-17 19:27:31 | healthy | 402 | 799ms | |
| 2026-09-17 08:46:45 | healthy | 402 | 757ms | |
| 2026-09-17 00:29:22 | healthy | 402 | 539ms | |
| 2026-09-16 17:16:05 | healthy | 402 | 1130ms | |
| 2026-09-16 09:11:03 | healthy | 402 | 894ms | |
| 2026-09-15 22:23:27 | healthy | 402 | 630ms | |
| 2026-09-15 16:50:30 | healthy | 402 | 553ms |