ToolsOpsAll tools
Full catalog. Every utility runs in your browser, with no install and without sending your data to a server.
Why this collection
ToolsOps groups calculators and converters that cover frequent tasks in DevOps, sysadmin and development: converting chmod permissions, planning IP networks, writing correct cron expressions and validating JSON or YAML. Every tool runs in your browser, never sends your input to a server, and keeps its scope tight: one clear operation rather than a generic editor that tries to do everything.
By category
Linux / Unix permissions
For when you read a permission like 755 or 4755 and need to know what it actually allows, or the other way round: you have an intent ("owner writes, everyone else only reads") and need the exact value. Covers special permissions setuid/setgid/sticky, the full symbolic notation and the default permissions umask applies to new files and directories.
- chmod calculator - octal permissions 755, 750 and 765
Convert between octal (755, 750, 765, 644), symbolic (rwxr-xr-x) and ls -l style permissions. Supports setuid, setgid and sticky bit.
- Umask calculator - default Linux permissions
Calculate the permissions new files and directories get from a umask. Explains 022, 027, 077 and 002 with octal and symbolic output.
IP networking and MAC addresses
Compute IPv4/IPv6 prefixes, ranges, usable hosts, IPv4 wildcard masks and subnet splits, plus look up the vendor of a MAC address by its OUI. Useful when planning subnets in a VPC, writing Cisco ACLs, identifying a device by its MAC or verifying what a script just produced. Includes FLSM splitter, VLSM planner, comparator and cheat sheet.
- IPv4/IPv6 CIDR and Subnet Calculator
IPv4/IPv6 CIDR and subnet calculator online: IPv4 masks and wildcard, IPv6 ranges, prefix splits and address totals in your browser.
- MAC vendor and OUI lookup
Identify the vendor of a MAC address or OUI, normalize common formats and flag locally administered, multicast, broadcast or unknown addresses without sending data to a server.
JSON / YAML validation and conversion
Validate a JSON before pasting it into a config, pretty-print it, minify it for production or convert between JSON and YAML without leaving your browser. Built for Kubernetes manifests, GitHub Actions workflows, Compose files and API contracts.
- Online JSON validator and formatter
Validate, pretty-print or minify JSON in your browser. Errors show line and column whenever the browser exposes them. The JSON is processed in your tab, not sent to a ToolsOps server.
- YAML to JSON and JSON to YAML Converter
Convert YAML to JSON and JSON to YAML in your browser. Nothing is sent to a server, no tracking, with clear error reporting.
DevOps and automation
Generate and validate Docker Compose files for local stacks (with volumes, healthchecks and ports bound to localhost), and create or read Unix/POSIX cron expressions, including the POSIX OR semantics on dom + dow that most documentation glosses over. Useful for spinning up local databases and services, operational configuration and scheduled maintenance tasks.
- Cron expression generator
Build, parse and explain 5-field Unix cron expressions. Computes the next runs in your local time zone.
- Docker Compose generator and validator
Generate a practical compose.yaml for common stacks (Postgres, MySQL, Redis, WordPress...), validate yours with an operational lint, and build correct healthchecks. All in your browser.
Hash, checksum and authentication
Compute the digest of text or files with SHA-256, SHA-1, SHA-384, SHA-512 or legacy MD5 to verify downloads; and decode or verify JWTs with HS256, RS256 or ES256 from the browser. Both tasks process data locally: neither the file, nor the token, nor the secret leaves the browser.
- Hash and checksum calculator (SHA-256, MD5, SHA-512)
Calculate SHA-256, SHA-1, SHA-384, SHA-512 and MD5 of text or files without sending anything to a server. Compare against an expected checksum to verify downloads. Everything runs in your browser.
- JWT decoder and verifier (HS256, RS256, ES256)
Decode the header and payload of a JWT and verify its signature with HS256/384/512, RS256/384/512 or ES256/384/512. Everything runs in your browser with Web Crypto API: the token, secret, and key never leave the page.
Unique identifiers
Generate and decode UUIDs in your browser. Random v4 for the general case and time-ordered v7 when you plan to use it as a primary key in databases. Validate existing UUIDs to detect version and variant. The generator uses the Web Crypto API and everything runs locally.
How to choose a tool
Start with the problem, not the name
If someone asks you to "open a port to this subnet", the right tool is the CIDR calculator even if they phrased it as "subnet mask". The index is grouped by domain precisely for that reason.
Verify with a known case
Before trusting any output, paste a case you already know (say, 755 or 192.168.1.0/24) and check the result matches your expectation. Good sanity check for both the maths and the current version.
Read the guide if there is one
Tools with an editorial guide attached (chmod, CIDR, cron) have a /guides/... page that explains the domain with context, examples and frequent pitfalls. It is the shortcut when the calculation itself is not the hard part.
Only paste what you would be comfortable emailing
The tools are client-side, but keep the professional habit: do not put production tokens, SSH private keys or real personal data into any field. Use synthetic examples for shared demos.