Toolbit
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Free, fast IT tools with no account required.

Toolbit brings together everyday calculators and utilities for networking, development, sysadmin, and security: an IPv4 subnet calculator, VLSM calculator, number base converter, secure password generator, cron expression parser, JSON formatter, Unix timestamp converter, Base64 and URL encoders, UUID generator, hash generator, and storage unit converter. Every tool runs entirely in your browser — no sign-up, no usage limits, and nothing you enter is ever sent to a server. Built for people working with networks, code, or infrastructure who need a fast, reliable answer without distractions or intrusive ads. The catalog keeps growing: if a tool you need isn't here yet, the next one is probably already on its way.

How it works

Every calculator processes input with JavaScript running on the visitor's own device — there's no backend receiving, storing, or logging what gets typed into a form, and no account to create to unlock a feature. That's not a marketing claim, it's a direct consequence of how the site is built: statically generated pages with no API route collecting those values. Each tool also ships with a companion article that includes worked examples and references to the relevant RFCs or technical specs, for anyone who wants to understand why a result came out the way it did, not just get the number.

Who Toolbit is for

  • Network admins who need to work out a subnet or split a block with VLSM without opening a spreadsheet.
  • Developers who want to validate JSON, Base64- or URL-encode a value, generate UUIDs, or convert a number between bases without installing anything.
  • Sysadmins who need to know what a cron expression does before scheduling it, convert a timestamp from a log, or explain why a drive shows less capacity than advertised.
  • Anyone who needs a genuinely random password or wants to verify the SHA-256 hash of a downloaded file, without the data leaving the browser.

Networking

Subnet CalculatorCalculate network, broadcast, host range and mask from an IP and CIDR prefix.VLSM CalculatorSplit a base network into variable-size subnets based on how many hosts each one needs.

Development

Base ConverterConvert numbers between binary, octal, decimal, and hexadecimal in real time.JSON Formatter & ValidatorFormat, minify, and validate JSON with precise syntax errors by line and column.Base64 Encoder & DecoderEncode text to Base64 and decode Base64 back to text, with UTF-8 support, the base64url variant, and optional padding.URL Encoder & DecoderPercent-encode and decode text for URLs, query parameters, and forms, and break a URL down into its parts and parameters.UUID GeneratorGenerate random UUID v4s and time-ordered UUID v7s, one at a time or in bulk, and inspect the version, variant, and timestamp of any UUID.

Sysadmin

Cron Expression ParserTranslate a cron expression into plain language and see its next executions.Unix Timestamp ConverterConvert Unix timestamps in seconds, milliseconds, or nanoseconds to a readable date in any time zone, and ISO 8601 dates back to timestamps.Storage Unit Converter (GB, GiB, Mbit)Convert between bytes, KB, MB, GB, TB and their binary counterparts KiB, MiB, GiB, TiB, and between bits and bytes, with a transfer time calculator.

Security

Password GeneratorGenerate random, secure passwords with configurable length and rules.Hash Generator (MD5, SHA-1, SHA-256, SHA-512)Compute MD5, SHA-1, SHA-256, SHA-384, and SHA-512 for text or a file, with optional HMAC, and compare the result against a published checksum.

Latest guides

See all guides
Subnetting from the Bits: How to Calculate a Subnet by HandWork out the network, broadcast, mask, and host range of any IPv4 subnet straight from the bits, with two step-by-step worked examples.VLSM Step by Step: A Worked ExampleA complete VLSM exercise on a /24 with six subnets of different sizes: block sizing, assignment order, and what to do when the address space runs out.Crontab: 20 Real-World Examples ExplainedTwenty cron expressions for real jobs, from every 5 minutes to month-end, plus the most common traps: the day-field OR rule, unescaped % signs, and daylight saving time.

Where to start

Four paths depending on the kind of work you do, each with the guides that explain the topic and the tools that solve it.

Networking

Start with how a subnet is worked out from the bits, then move on to a complete VLSM exercise. With that foundation, the two calculators let you check any addressing plan before you configure it.

Systems

Scheduled jobs and dates break for the same reasons: time zones, daylight saving time, and mixed-up units. The guides cover those cases, and the tools let you check a cron expression, a timestamp, or a disk capacity before it goes to production.

Development

For day-to-day work with data: validate JSON, Base64- or URL-encode values knowing what each variant changes, and choose between UUID v4 and v7 based on how the identifiers will be used.

Security

How many bits of entropy a password needs, which hash function fits which job, and why SHA-256 is right for verifying a download but wrong for storing passwords.

How results are verified

A technical calculator is only useful if you can trust its output. That's why each tool's logic is kept separate from its interface and covered by automated tests that compare its output against reference values: network and broadcast addresses worked out by hand, the /31 and /32 special cases defined in RFC 3021, valid and invalid JSON documents per RFC 8259, the official test vectors for Base64 (RFC 4648), MD5 (RFC 1321), HMAC (RFC 4231), and UUIDs (RFC 9562), cron expressions with known upcoming runs, and timestamp conversions checked against the IANA time zone database.

The guides follow the same standard. Every worked example (a subnet, a VLSM allocation, a cron expression, a clock change) is also computed with the matching tool's code before it's published, and the example's link opens the tool with those same values so anyone can check it.

When a tool makes a call that isn't obvious — treating a /31 as a point-to-point link, or deciding whether a timestamp is in seconds or milliseconds — the article that comes with it explains the rule and cites the specification it comes from. If a result doesn't match the standard, the contact page explains how to report it.