cron2systemd.dev
DevOps utilities that run in your browser
Thirty-one 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.
OnCalendar ↔ crontab converter
Bidirectional systemd timer OnCalendar= to 5-field crontab translator with plain-English explanations and quirk notes.
SchedulingCron to systemd timer
Convert a crontab schedule into a systemd .service plus .timer with OnCalendar=, Persistent=, and a oneshot ExecStart.
SchedulingCrontab generator
Build a 5-field cron expression from dropdowns and get an English explanation of when it fires.
systemdsystemd service builder
Generate a systemd unit file from ExecStart, Restart, User, Environment, and hardening toggles.
Fileschmod permissions calculator
Convert Unix file modes both ways: 755 ↔ rwxr-xr-x, with setuid, setgid, and sticky bits.
NetworkCIDR subnet calculator
Expand an IPv4 CIDR into netmask, network, broadcast, usable host range, and host count.
TimeUnix epoch converter
Convert between Unix timestamps (seconds or milliseconds) and human-readable UTC / local datetimes.
Authhtpasswd generator
Create Apache htpasswd lines entirely in the browser using {SHA} Base64(SHA-1) via Web Crypto.
Containersdocker run → Compose
Parse a docker run command and emit a Compose service YAML snippet with ports, env, volumes, and restart policy.
Networknginx reverse proxy builder
Generate an nginx server block for reverse proxying, with TLS, WebSocket upgrade headers, and body-size limits.
NetworkCaddyfile generator
Build a Caddyfile reverse-proxy site block with automatic HTTPS and optional gzip encoding.
Authssh-keygen command builder
Compose a safe ssh-keygen invocation for ed25519 (or RSA/ECDSA) with comment, path, and KDF rounds.
ContainersKubernetes Secret encoder
Base64-encode multi-line values into a Kubernetes Secret YAML manifest using TextEncoder (UTF-8).
HTTPcURL to Python
Translate a curl command into Python requests and httpx client code, including headers, auth, and JSON bodies.
DataJSON to YAML converter
Convert JSON objects and arrays to YAML with a small in-browser emitter — no libraries.
NetworkKeepalive timeout calculator
Estimate proxy idle timeouts, upstream keepalive pools, and concurrency from RPS, latency, and backend count.
NetworkBIND DNS record formatter
Turn A, CNAME, TXT, and MX fields into BIND zone-file lines with TTL and origin.
systemdjournalctl filter builder
Assemble a journalctl command from unit, priority, time window, boot, and output format.
Networkiptables rule builder
Build allow/drop ingress and egress iptables (or ip6tables) rules with protocol, port, and connection state.
DataUUID v4 generator
Generate cryptographically random RFC 4122 UUID version 4 values, one at a time or in bulk.
DataRegex cheatsheet tester
Test JavaScript / grep / sed-style regular expressions against sample text with a POSIX vs PCRE cheatsheet.
ContainersDockerfile explainer
Lint a Dockerfile and explain each instruction, including floating tags, root, ADD versus COPY, and apt layers.
ContainersCompose port and volume map
Explain Compose port publishes and volume mounts: host versus container, protocol, and bind versus named volume.
ContainersImage reference parser
Split a container image reference into registry, repository, tag, and digest, and flag floating tags.
ContainersKubernetes resource units
Convert Kubernetes CPU and memory quantities between cores, millicores, bytes, and SI or binary suffixes.
ContainersKubernetes DNS names
Build Kubernetes DNS names for a Service, a named-port SRV, a headless Pod, and a Pod IP.
NetworkDNS record validator
Check A, AAAA, CNAME, MX, TXT, SRV, and CAA rdata and show a normalized record line.
NetworkSPF record builder
Build an SPF TXT record and check qualifiers, mechanisms, and the 10-lookup limit.
NetworkDMARC record builder
Build a DMARC TXT record for _dmarc with policy, alignment, reporting URIs, and pct.
NetworkTTL and duration converter
Convert a DNS TTL or a systemd-style duration into seconds, a BIND unit string, and plain English.
NetworkReverse DNS generator
Turn an IPv4 or IPv6 address into an in-addr.arpa or ip6.arpa PTR owner name.