free dev tools · ai-powered

Developer tools for the two-minute problems, with AI built in.

Formatters, converters, token counters, and model calculators built for the gap between opening your terminal and finishing your coffee. No account, no clutter, nothing uploaded.

token-counter.kwk
// count tokens before you ship
in  "Summarize this thread in one line."
out
tokens 9
gpt-4o $0.00002
claude $0.00003
$ ready
the toolbox

Pick a problem, get it solved.

19 developer tools, including a growing set of AI helpers. Each does exactly one job, instantly, in your browser.

Formatter

JSON Formatter

Paste ugly JSON, get clean, validated, color-coded output.

open tool
Converter

Base64 Encode / Decode

Text and file conversion, both directions, instantly.

open tool
Generator

UUID / GUID Generator

Bulk-generate v4 UUIDs in any format you need.

open tool
New · AI

AI Token Cost Calculator

Estimate spend across Claude, GPT, and Gemini before you build.

open tool
Compare

Text Diff Checker

Side-by-side diff for code, config, or plain text.

open tool
New · AI

AI Disclosure Snippet

Generate compliant "AI-generated content" labels for your site.

open tool
Decoder

JWT Decoder

Decode a JSON Web Token's header and payload, no secret needed.

open tool
Generator

Hash Generator

MD5, SHA-1, SHA-256, SHA-512 checksums from any text.

open tool
Converter

URL Encode / Decode

Percent-encode text for URLs, or decode it back.

open tool
Converter

Unix Timestamp Converter

Convert between Unix time and human dates, both ways.

open tool
Text

Case Converter

camelCase, snake_case, kebab-case, Title Case, and more.

open tool
Converter

Color Converter

Convert colors between HEX, RGB, and HSL with a live preview.

open tool
New · AI

AI Token Counter

Count real tokens for GPT prompts, right in your browser.

open tool
New · AI

LLM Model Comparison

Compare context windows, pricing, and modalities across models.

open tool
New · AI

AI Prompt Builder

Compose a structured, best-practice prompt from clear sections.

open tool
New · AI

llms.txt Generator

Generate an llms.txt file to guide AI crawlers to your best content.

open tool
New · AI

JSON Schema Builder

Build JSON Schema for LLM structured outputs and function calling.

open tool
Text

Regex Tester

Test regular expressions live, with match and group highlighting.

open tool
New · AI

AI Repo & Multi-File Token Calculator

Drag & drop multiple files to calculate LLM tokens, context fit, and spend.

open tool