$ whoami
→ a play-school for backend & CLI nerds, one subdomain per topic.
$ uname -a
→ CertuviaOS 1.0 · 8 mounted playgrounds · zero paywalls
$ ./boot
statushosttaglinemissions
[live]git.certuvia.comcommit · branch · merge71
[live]postgres.certuvia.comthe database that grew up104
[soon]bun.certuvia.comthe fast JS runtime28
[soon]regex.certuvia.com/^learn|grok$/24
[soon]sqlite.certuvia.coma database in a single file18
[soon]crypto.certuvia.comkeys · certs · signatures22
[soon]ssh.certuvia.comremote shells & tunnels16
[soon]nginx.certuvia.comreverse proxy mastery20
FROM THE BLOG / READ IT, RUN ITAll articles ↗
PostgreSQL 19: less friction, more control
A practical tour of the maintenance, planning, and replication changes worth watching.
─── git.certuvia.com ───
[live]
⎇
Git
commit · branch · merge
$ man git
NAME
Git — commit · branch · merge
DESCRIPTION
Version control from "what is a commit" to rebasing like a maniac.
Browse curriculum · 71 lessons available →PLAYGROUND
domain: git.certuvia.com
missions: 71
cost: $0
install: none required
missions: 71
cost: $0
install: none required
▸typeopen git.certuvia.comto launch
─── postgres.certuvia.com ───
[live]
🐘
Postgres
the database that grew up
$ man postgres
NAME
Postgres — the database that grew up
DESCRIPTION
SQL, indexes, EXPLAIN, JSONB, CTEs, window functions, and tuning.
Browse curriculum · 104 lessons available →PLAYGROUND
domain: postgres.certuvia.com
missions: 104
cost: $0
install: none required
missions: 104
cost: $0
install: none required
▸typeopen postgres.certuvia.comto launch
─── bun.certuvia.com ───
[soon]
🥟
Bun
the fast JS runtime
$ man bun
NAME
Bun — the fast JS runtime
DESCRIPTION
Ship JS/TS without webpack purgatory. Bun-native APIs, bundling, testing.
Coming soonPLAYGROUND
domain: bun.certuvia.com
missions: 28
cost: $0
install: none required
missions: 28
cost: $0
install: none required
▸typeopen bun.certuvia.comto launch
8
mounted playgrounds
175
micro-missions
0
paywalls or popups
24/7
sandbox uptime
─── regex.certuvia.com ───
[soon]
/.*/
Regex
/^learn|grok$/
$ man regex
NAME
Regex — /^learn|grok$/
DESCRIPTION
Stop fearing the squiggles. Patterns, lookarounds, anchors, real-life cases.
Coming soonPLAYGROUND
domain: regex.certuvia.com
missions: 24
cost: $0
install: none required
missions: 24
cost: $0
install: none required
▸typeopen regex.certuvia.comto launch
─── sqlite.certuvia.com ───
[soon]
◇
SQLite
a database in a single file
$ man sqlite
NAME
SQLite — a database in a single file
DESCRIPTION
The tiny DB that runs everywhere. Schemas, FTS, WAL, embedded patterns.
Coming soonPLAYGROUND
domain: sqlite.certuvia.com
missions: 18
cost: $0
install: none required
missions: 18
cost: $0
install: none required
▸typeopen sqlite.certuvia.comto launch
─── crypto.certuvia.com ───
[soon]
🔐
OpenSSL & Crypto
keys · certs · signatures
$ man openssl
NAME
OpenSSL & Crypto — keys · certs · signatures
DESCRIPTION
Demystify TLS, X.509, hashing and signing without crying into your terminal.
Coming soonPLAYGROUND
domain: crypto.certuvia.com
missions: 22
cost: $0
install: none required
missions: 22
cost: $0
install: none required
▸typeopen crypto.certuvia.comto launch
─── /etc/manifesto.txt ───
est. 1592
$ cat /etc/manifesto.txt
// schola ludus
Quick story. Dude born in 1592 in Czech, name's Jan Amos Komenský — Latin nerds called him Comenius. Centuries before "edutech" was a buzzword, he wrote that **schola ludus** — "school as a play / a game" — is the way humans actually learn. Not lectures. Not memorizing gaslit textbooks at 6am. Play. That's basically the whole pitch of Certuvia. You don't really learn `git rebase -i` from a 40-minute video — you learn it by breaking a fake repo, getting a tiny hint, fixing it, and feeling that little dopamine click. Same for regex, for SQL, for SSH tunnels. We just try to do what a 17th-century Moravian guy already figured out: make the playground, hand you the tools, get out of the way.
─── ssh.certuvia.com ───
[soon]
⌁
SSH
remote shells & tunnels
$ man ssh
NAME
SSH — remote shells & tunnels
DESCRIPTION
Keys, agents, port forwarding, jump hosts, and config files that just work.
Coming soonPLAYGROUND
domain: ssh.certuvia.com
missions: 16
cost: $0
install: none required
missions: 16
cost: $0
install: none required
▸typeopen ssh.certuvia.comto launch
─── nginx.certuvia.com ───
[soon]
λ
NGINX
reverse proxy mastery
$ man nginx
NAME
NGINX — reverse proxy mastery
DESCRIPTION
Serve static, proxy backends, terminate TLS, cache like a pro.
Coming soonPLAYGROUND
domain: nginx.certuvia.com
missions: 20
cost: $0
install: none required
missions: 20
cost: $0
install: none required
▸typeopen nginx.certuvia.comto launch
$ man faq
FREQUENTLY-ASKED-QUESTIONS(7)
▸ is it free?
Yes. apt install certuvia returns: free.
▸ install required?
No. Browser-only. Sandboxed in a tab.
▸ who is this for?
Devs who keep meaning to actually learn the CLI stuff.