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Subnet Calculator
Calculate network address, broadcast address, and usable IP ranges for IPv4/IPv6.
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Developer Tools
Format JSON, convert encodings, and translate Unix timestamps. The utilities you open ten times a day.
13 tools in this category
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CHMOD Configurator
Calculate Linux file permissions using checkboxes or octal numbers, then view the matching symbolic notation.
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Cron Generator
Visually build standard 5-part cron expressions or translate them into readable schedules.
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Open Graph Visualizer
Preview how your website links will look when shared on Google, Twitter, Facebook, and Discord.
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LLM VRAM Calculator
Calculate the VRAM needed to run or fine-tune any LLM at any quantization.
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LLM API Pricing Calculator
Compare API costs across major models (OpenAI, Anthropic, Google) with prompt caching.
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LLM Token Counter
Count tokens in any prompt for GPT, Claude, Gemini, and Llama with exact OpenAI tokenization.
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Character Counter
Count characters, words, sentences, paragraphs, and lines. Check writing limits and count specific characters or phrases.
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Text Encoding Converter
Convert between Text, Base64, Binary, Hexadecimal, and Decimal formats.
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JSON Formatter
Validate, format, and minify JSON data with readable output and error detection.
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Unix Timestamp
Convert between Unix timestamps and human-readable dates.
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GitHub Actions Runner Benchmarks
Compare independent runner CPU, disk, cache, and network tests with hardware mappings and per-vCPU minute prices.
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Frequency Generator
Play tones and selectable waveforms from 20 Hz to 20 kHz, stack up to four oscillators, and A/B compare two presets.
Use Tool ➜About Developer Tools
TechCompare's developer tools are the small utilities you reach for a dozen times a day: a JSON formatter that pretty-prints and validates with clear error messages, an encoding converter that moves text between UTF-8, Base64, binary, hex, and decimal, and a Unix timestamp converter that handles seconds, milliseconds, and timezones in both directions.
All three run entirely in the browser, so you can paste production payloads without worrying about a server logging them. They're designed to be fast enough to belong in your muscle memory. Open the tab, paste, copy the result, close the tab. The collection also includes networking and permission helpers like the /28 subnet calculator and the chmod 600 permissions reference.
Frequently asked questions
Does the JSON Formatter send my data anywhere?
No. Formatting, validating, and minifying all happen in your browser via the built-in JSON.parse and JSON.stringify APIs. You can disconnect from the internet after the page loads and it continues to work.
Can I decode a JWT with the Encoding Converter?
Why is my Unix timestamp giving me a date in 1970?
You're almost certainly passing a seconds value to a milliseconds API, or vice versa. The Unix Timestamp tool has a manual seconds-versus-milliseconds choice, so select the unit that matches the value before converting it.
Can the JSON Formatter handle huge payloads?
It can handle anything your browser's memory can hold, typically tens of megabytes without issue. For multi-GB files use a streaming tool; for anything you'd reasonably paste, it's fine.
Are these tools free for commercial use?
Yes. No accounts, no rate limits, no paid tier. They're free to use at work, on personal projects, or anywhere else.