# Developer Utilities

JWT decoding, iCalendar builder, breached-password check, certificate transparency, cron schedules, regex tester, user-agent parser.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://dev-utils.x402tookit.com/openapi.json
- x402 manifest: https://dev-utils.x402tookit.com/.well-known/x402
- Catalog (free): https://dev-utils.x402tookit.com/catalog
- Health (free): https://dev-utils.x402tookit.com/health
- Uptime (free): https://dev-utils.x402tookit.com/uptime

## Endpoints (7)

### GET /cert-transparency — $0.02
Certificates in Certificate Transparency logs for a domain: recent certs, issuers, subdomains seen (Cert Spotter).
Params: domain: string
Example: https://dev-utils.x402tookit.com/cert-transparency?domain=iana.org

### GET /cron-next-runs — $0.02
Next N run times for a 5-field cron expression in a chosen UTC offset, with the day-of-month/day-of-week OR rule.
Params: expr: string, n?: integer, utc_offset?: string, from?: string
Example: https://dev-utils.x402tookit.com/cron-next-runs?expr=30+9+13+*+5&n=5&utc_offset=%2B05%3A30&from=2026-01-01T00%3A00%3A00Z

### GET /ics-event — $0.02
Build an RFC 5545 .ics calendar event from title, start, end, location, description; escaped and folded.
Params: title: string, start: string, end?: string, location?: string, description?: string, uid?: string
Example: https://dev-utils.x402tookit.com/ics-event?title=Team+sync%2C+planning%3B+Q2&start=2026-03-01T09%3A00%3A00-05%3A00&end=2026-03-01T10%3A00%3A00-05%3A00&location=Conference+Room+-+F123%2C+Bldg.+002&description=Agenda%3A%0Aroadmap%2C+budget

### GET /jwt-decode — $0.02
Decode a JWT header and payload (no signature check) and flag alg none, expiry, nbf and missing claims.
Params: token: string, now?: string
Example: https://dev-utils.x402tookit.com/jwt-decode?token=eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk

### GET /pwned-password — $0.02
Seen in breaches? Send the password's SHA-1 (never the password); only 5 hex chars go upstream. Count and verdict.
Params: sha1: string
Example: https://dev-utils.x402tookit.com/pwned-password?sha1=21BD12DC183F740EE76F27B78EB39C8AD972A757

### GET /regex-test — $0.02
Run a JS regex on text: matches, groups, indexes. Capped input and a time budget stops catastrophic backtracking.
Params: pattern: string, text: string, flags?: string
Example: https://dev-utils.x402tookit.com/regex-test?pattern=%28%3F%3Cyear%3E%5Cd%7B4%7D%29-%28%5Cd%7B2%7D%29&text=Released+2026-03%2C+patched+2026-05.&flags=g

### GET /user-agent-parse — $0.02
Parse a User-Agent string: browser, OS, device class (desktop, mobile, tablet, tv, bot) and a bot flag.
Params: ua: string
Example: https://dev-utils.x402tookit.com/user-agent-parse?ua=Mozilla%2F5.0+%28iPhone%3B+CPU+iPhone+OS+17_1+like+Mac+OS+X%29+AppleWebKit%2F605.1.15+%28KHTML%2C+like+Gecko%29+Version%2F17.1+Mobile%2F15E148+Safari%2F604.1

## Terms

Results are computed from the input you send or from public sources, provided as is, with no warranty. A JWT is decoded, never verified. Do not send real secrets in a query string; use the hash form for passwords.