Tools
Free Linux, homelab, and developer tools that run in your browser. Nothing is uploaded. Use them when you need a command, a calculation, or a quick reference, then jump back to the how-to posts when you want the longer explanation.
Linux
Btrfs RAID Calculator
Estimate usable Btrfs space for RAID1, RAID1c3, RAID10, and other profiles, including mixed disk sizes, then copy a mkfs.btrfs command.
Chmod Calculator
Convert Linux file permissions between octal and symbolic notation, then copy a ready-to-run chmod command.
Cron Expression Builder
Build a Linux crontab from dropdowns or a pasted expression, then copy the line, a plain-English schedule, next run times, and OnCalendar=.
Netplan Generator
Build Ubuntu Netplan YAML for ethernet or Wi-Fi — DHCP or static IP, DNS, and routes — then copy or download a file you can drop in /etc/netplan/.
Package Manager Cheat Sheet
Pick a Linux or BSD distro from the dropdown and copy the matching command — refresh, install, remove, or the update-and-reboot one-liner.
RAID Calculator
Work out usable capacity for mdadm RAID 0, 1, 5, 6, and 10 from your disk count and sizes, then copy a ready-to-run mdadm command.
Systemd Service Generator
Build a systemd .service and optional .timer from Type, User, Restart, and OnCalendar, then copy files for /etc/systemd/system/ or a user unit dir.
ZFS Capacity Calculator
Estimate usable ZFS pool space for mirrors, RAIDZ1, RAIDZ2, and RAIDZ3, including slop space, then copy a zpool create command.
Networking
Dual-Stack CIDR Calculator
Dual-stack CIDR calculator: work out IPv4 masks and IPv6 prefixes on one page, with network ranges, host counts, and copy-ready CIDR.
IPv4 CIDR Calculator
Convert an IPv4 address and prefix or subnet mask into network, broadcast, usable hosts, and wildcard — then copy the CIDR.
IPv6 CIDR Calculator
Expand or compress an IPv6 address, apply a prefix length, and see the network range, address count, and ip6.arpa PTR.
RJ45 Pinout
T568A vs T568B color order, straight-through vs crossover, and a copy-ready wire sequence for RJ45 ethernet cables.
Hardware
Capacitor Code Calculator
Decode ceramic EIA codes like 104 to nF and µF, or type 100nF to get the marking, tolerance, and range.
LED Resistor Calculator
Find the current-limiting resistor for an LED: ohm value, nearest E12/E24 part, wattage, and color bands.
Resistor Color Code Calculator
Read 4-, 5-, and 6-band resistor color codes, or type a value like 4.7 kΩ to see the bands, tolerance, and range.
Programming
Base64 Encoder/Decoder
Encode and decode Base64, including UTF-8, URL-safe alphabet, and MIME wrap.
Color Converter
Convert colors between HEX, RGB, and HSL, then copy CSS-ready values.
File Checksum
Hash a local file to SHA-256, MD5, SHA-1, SHA-384, or SHA-512 and compare it to an expected digest.
File Size Converter
Convert bytes, KB, KiB, MB, GB, and TB (SI 1000 vs IEC 1024), including why a 1 TB drive shows as 931 GiB.
Hash Generator
Hash text to MD5, SHA-1, SHA-256, SHA-384, or SHA-512, with optional HMAC and a paste-to-compare check.
JSON Formatter/Validator
Pretty-print, minify, and validate JSON — catch syntax errors with line and column, then copy or download.
MongoDB ObjectId Converter
Convert a MongoDB ObjectId to a Unix timestamp, or mint an ObjectId from a date.
Unix Timestamp Converter
Convert Unix epoch seconds or milliseconds to UTC and local dates, or pick a date and copy a timestamp.
UUID Generator
Generate UUID v4 and time-ordered UUID v7 (GUIDs), then bulk-copy or validate.