cron2systemd.dev

DevOps utilities that run in your browser

Twenty client-side converters and builders for cron, systemd, nginx, Docker, DNS, and the other snippets you always end up grepping man pages for. The original OnCalendar ↔ crontab translator is included so this hub can be the static-host output root without dropping the flagship tool.

Flagship converter

OnCalendar ↔ crontab converter

Bidirectional systemd timer OnCalendar= to 5-field crontab translator with plain-English explanations and quirk notes.

Scheduling

Cron to systemd timer

Convert a crontab schedule into a systemd .service plus .timer with OnCalendar=, Persistent=, and a oneshot ExecStart.

Scheduling

Crontab generator

Build a 5-field cron expression from dropdowns and get an English explanation of when it fires.

systemd

systemd service builder

Generate a systemd unit file from ExecStart, Restart, User, Environment, and hardening toggles.

Files

chmod permissions calculator

Convert Unix file modes both ways: 755 ↔ rwxr-xr-x, with setuid, setgid, and sticky bits.

Network

CIDR subnet calculator

Expand an IPv4 CIDR into netmask, network, broadcast, usable host range, and host count.

Time

Unix epoch converter

Convert between Unix timestamps (seconds or milliseconds) and human-readable UTC / local datetimes.

Auth

htpasswd generator

Create Apache htpasswd lines entirely in the browser using {SHA} Base64(SHA-1) via Web Crypto.

Containers

docker run → Compose

Parse a docker run command and emit a Compose service YAML snippet with ports, env, volumes, and restart policy.

Network

nginx reverse proxy builder

Generate an nginx server block for reverse proxying, with TLS, WebSocket upgrade headers, and body-size limits.

Network

Caddyfile generator

Build a Caddyfile reverse-proxy site block with automatic HTTPS and optional gzip encoding.

Auth

ssh-keygen command builder

Compose a safe ssh-keygen invocation for ed25519 (or RSA/ECDSA) with comment, path, and KDF rounds.

Containers

Kubernetes Secret encoder

Base64-encode multi-line values into a Kubernetes Secret YAML manifest using TextEncoder (UTF-8).

HTTP

cURL to Python

Translate a curl command into Python requests and httpx client code, including headers, auth, and JSON bodies.

Data

JSON to YAML converter

Convert JSON objects and arrays to YAML with a small in-browser emitter — no libraries.

Network

Keepalive timeout calculator

Estimate proxy idle timeouts, upstream keepalive pools, and concurrency from RPS, latency, and backend count.

Network

BIND DNS record formatter

Turn A, CNAME, TXT, and MX fields into BIND zone-file lines with TTL and origin.

systemd

journalctl filter builder

Assemble a journalctl command from unit, priority, time window, boot, and output format.

Network

iptables rule builder

Build allow/drop ingress and egress iptables (or ip6tables) rules with protocol, port, and connection state.

Data

UUID v4 generator

Generate cryptographically random RFC 4122 UUID version 4 values, one at a time or in bulk.

Data

Regex cheatsheet tester

Test JavaScript / grep / sed-style regular expressions against sample text with a POSIX vs PCRE cheatsheet.