github-user-checker

Checks if GitHub username can really be registered. Go, zero deps. Every proxy runs its own workers off one shared queue, own connection joins at a rate limit. Free names go to text file.

Why not 404

GET github.com/<name> → 404 lies:

name	github.com/<name>	api.github.com/users/<name>	truth
admin	404	404	reserved, never registrable
zzzqqxxwv	404	404	free

Same answer, different truth. This tool asks what signup form asks, github.com/signup_check/username?value=<name>. Three answers:

• 200 + <name> is available. → free
• 422 + Username <name> is not available. → taken
• 422 + Username '<name>' is unavailable. → reserved

Verified live 2026-09-09.

No false positives

1. Response must carry X-GitHub-Request-Id. Proxy error page cannot fake it. No header → answer thrown away, name retried elsewhere.
2. Every hit re-checked through second route before written. One yes not enough.
3. GitHub 429 is real answer, not proxy fault. Proxy stays, name moves on.
4. Names breaking GitHub rules (leading/trailing/double hyphen, >39 chars) dropped before request spent.

Tested: 13 known names over free proxies, 4 free / 4 taken / 4 reserved / 1 taken-with-hyphen. 13/13 correct. Random sample of 2032 earlier hits, 8/8 still free.

Run

go build -o ghcheck .
./ghcheck -in wordlists/englishlowercase.txt

Hits → available.txt as found. Every decided name → checked.txt. Ctrl+C, run again, resumes.

Flags

flag	default	meaning
-in	wordlists/dutchlowercase.txt	wordlist, one name per line
-out	available.txt	free names
-done	checked.txt	resume log
-proxies	proxies.txt	proxy list
-direct	true	own connection joins the pool, rate limited
-direct-rate	30	direct requests per minute, 0 unlimited
-per-proxy	4	concurrent requests through each proxy
-tries	8	failures from proven proxies (or 429s) per name before giving up
-backoff	10s	pause after a proxy fails, doubles each failure in a row
-max-backoff	10m	longest pause for a failing proxy
-limit-pause	20s	pause for a proxy GitHub answered 429 to
-reload	2m	re-read proxy list this often, 0 off
-min / -max	2 / 8	name length filter
-letters	true	keep only a-z
-confirm	true	re-check hits via second route
-timeout	8s	per request
-debug	false	print why each attempt rejected

Proxies

proxies.txt, one per line:

http://1.2.3.4:8080
https://user:pass@1.2.3.4:8443
socks4://5.6.7.8:1080
socks5://user:pass@9.10.11.12:1080

Bare host:port = http. SOCKS handshakes implemented here, no deps. File gitignored.

Two rules:

• Proxy must CONNECT to https. GitHub is TLS. Lists validated against plain-http target fail every request.
• Free proxies die in hours. Dead proxy never retired, only paused: -backoff doubling per failure up to -max-backoff, then probed again. Fast proxies pull most names, dead ones cost only their own time. -reload picks up new entries mid-run.

No list, or all dead → run continues direct at -direct-rate. Slow on purpose. One address, nothing behind it.

Notes

• Endpoint answers 406 to any Accept list. Send exactly one: text/fragment+html.
• Reserved counted separate from taken. Neither written to output.