06 / Tools Free utilities for builders

Tools.

Practical tools built from real engagement patterns. Open, instant, no signup required.

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YAML ↔ JSON Converter

Convert between YAML and JSON instantly — bidirectional, client-side, with syntax validation.

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Word Counter & Reading Time

Count words, characters, and sentences in real time — plus reading time, speaking time, and keyword density.

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UUID Generator

Generate cryptographically random v4 UUIDs in bulk — all client-side.

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URL Encode/Decode

Encode and decode URLs and URI components instantly — all client-side.

Unix Timestamp Converter

Convert between Unix timestamps and human-readable dates — all client-side.

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Unit Converter

Convert between units of length, weight, temperature, data size, time, and more — all client-side.

TOTP Code Generator

Generate time-based one-time passwords from a secret key — runs entirely in your browser.

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Tool Index & Search

Search and browse all 100 tools with categories, descriptions, and direct links.

Token Counter

Estimate token counts for GPT-4, GPT-3.5, and Claude 3 models. See character count, word count, and per-model token estimates in real time.

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Tip Calculator

Calculate tip amounts and split bills evenly among any number of people.

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Timezone Converter

Compare times across multiple timezones at a glance — with business hours highlighting and common region presets.

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Tech Stack Visualizer

Select your tech stack components and generate a shareable visual diagram.

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Tailwind CSS Class Lookup

Search Tailwind CSS utility classes instantly — see what each class does with live CSS output and visual previews.

System Prompt Linter

Paste a system prompt and get instant feedback on anti-patterns, vague language, missing structure, and an overall quality score.

SVG Path Editor

Draw and edit SVG paths visually — drag control points, see commands in real time, and export clean SVG code.

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Subresource Integrity Hash

Generate SRI hashes for scripts and stylesheets to protect against CDN tampering.

Subnet Calculator

Parse CIDR notation and instantly see network address, broadcast, netmask, usable host range, and IP class.

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Standup Note Generator

Build structured standup notes and export them as plain text, Markdown, or Slack-formatted messages.

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SSL Certificate Decoder

Paste a PEM-encoded certificate and instantly view subject, issuer, validity, SANs, and key details.

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SSH Key Generator

Generate Ed25519 or RSA key pairs entirely in the browser — nothing leaves your machine.

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SQL Formatter

Pretty-print and format SQL queries with syntax highlighting — all client-side.

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Sprint Velocity Calculator

Track sprint velocity, visualize trends, and forecast delivery timelines with confidence ranges.

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Slug Generator

Convert any text into URL slugs, filenames, CSS classes, camelCase, and snake_case in real time.

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Sitemap XML Generator

Generate a valid XML sitemap with per-URL priority, changefreq, and lastmod settings.

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SaaS Unit Economics Dashboard

Input your key SaaS metrics and get a one-page unit economics snapshot with health indicators and actionable benchmarks.

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Runway Calculator

Enter your cash on hand, monthly revenue, and expenses to calculate your startup's runway, burn rate, and zero-cash date.

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Robots.txt Generator

Build a robots.txt file with user-agent rules, presets for AI bots, sitemap URL, and crawl-delay.

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Retro Board

Run sprint retrospectives with draggable cards, voting, and markdown export. Organize feedback into What Went Well, What Didn't, and Action Items.

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Responsive Breakpoint Tester

Preview any URL at common viewport sizes — test mobile, tablet, and desktop breakpoints side by side.

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Regex Tester

Test regular expressions with real-time match highlighting and group capture display — all client-side.

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README Template Generator

Fill in project details and generate a well-structured README.md file.

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Readability Score Analyzer

Analyze text readability using Flesch, Gunning Fog, Coleman-Liau, and other industry-standard formulas.

RAG Retrieval Debugger

Debug retrieval quality by scoring text chunks against a query using BM25 and TF-IDF cosine similarity. See rankings, scores, and highlighted term matches.

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QR Code Generator

Generate QR codes from any text or URL — download as PNG, all client-side.

Prompt Template Builder

Write prompt templates with {{variable}} placeholders, fill in each variable, and preview the rendered prompt ready to copy.

Prompt A/B Tester

Draft, compare, and diff two prompts side by side. See character, word, and token counts, highlight differences, and export as JSON.

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Project Scope Estimator

Estimate project hours and costs using t-shirt sizing for each feature or task.

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Privacy Policy Generator

Answer a few questions about your site or app and get a basic privacy policy draft — free and instant.

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Pricing Page Grader

Score your SaaS pricing page against a 20-point checklist of conversion best practices used by top-performing companies.

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Pomodoro Timer

Stay focused with timed work sessions and breaks — 25 minutes on, 5 minutes off, with audio alerts and session tracking.

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Password Strength Meter

Estimate crack time with zxcvbn-style pattern analysis — checks dictionary words, sequences, and common patterns.

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Password Generator

Generate strong, random passwords with configurable length, character sets, and real-time entropy display.

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Open Graph Preview

Preview how your URLs will appear when shared on Facebook, Twitter, Discord, LinkedIn, and Slack.

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Number Base Converter

Convert numbers between binary, octal, decimal, and hexadecimal — with live updates as you type.

Nginx Config Generator

Build production-ready nginx server blocks with SSL, reverse proxy, PHP-FPM, and security headers.

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MRR / ARR Calculator

Input your subscription tiers and customer counts to instantly calculate MRR, ARR, and month-over-month growth rate.

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Mortgage Payment Calculator

Estimate monthly mortgage payments with principal, interest rate, and loan term.

Model Context Window Comparison

Visual bar chart comparing context window sizes across GPT, Claude, Gemini, Llama, Mistral, and Cohere models. See what fits in each window.

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Meta Tag Generator

Generate Open Graph, Twitter Card, and SEO meta tags for any webpage instantly.

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Meeting Cost Calculator

Calculate the true cost of meetings based on attendees, hourly rates, and duration — including recurring meeting projections.

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Markdown to HTML Converter

Convert Markdown to HTML instantly with live preview — supports headings, tables, code blocks, and more.

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Markdown Table Generator

Build tables visually with a GUI editor and export clean Markdown — no syntax to remember.

LTV:CAC Ratio Calculator

Calculate customer lifetime value vs. acquisition cost, see your LTV:CAC ratio, and benchmark against SaaS industry standards.

Lorem Ipsum Generator

Generate placeholder text as paragraphs, sentences, or words — all client-side.

Keyboard Shortcut Reference

Searchable database of keyboard shortcuts for VS Code, Vim, Mac OS, and Windows.

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JWT Decoder

Paste a JSON Web Token and instantly decode the header, payload, and signature — all client-side.

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JSON to CSV Converter

Paste a JSON array and flatten it into a downloadable CSV file — all client-side.

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JSON Schema Generator

Paste a JSON example and instantly generate a JSON Schema with inferred types, required fields, nested objects, and format detection.

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JSON Formatter & Validator

Format, validate, and minify JSON with syntax highlighting — all client-side.

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Invoice Generator

Fill in your business details, add line items, and download a professional PDF invoice — no account needed, all client-side.

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Image to Base64 Encoder

Drop an image and get a ready-to-use data URI — all client-side, nothing uploaded.

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HTTP Status Code Reference

Searchable reference for every HTTP status code with descriptions, use cases, and quick copy.

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HTTP Header Analyzer

Paste HTTP response headers and get actionable security recommendations for hardening your site.

Hourly Rate Calculator

Convert your desired annual salary into an hourly rate with overhead and profit margins.

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Headline Analyzer

Score and optimize headlines for engagement — analyzes length, power words, sentiment, and word balance.

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Hash Generator

Generate SHA-256, SHA-512, and MD5 hashes from any text input — all client-side.

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Gantt Chart Builder

Build interactive Gantt charts with tasks, dependencies, and timeline visualization. Add tasks with dates, draw dependency arrows, and export your project plan.

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Font Pairing Suggester

Pick a heading font and get expert body font pairings — preview them live with customizable sample text.

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Feature Prioritization Matrix

Score and rank features using ICE or RICE frameworks with a sortable, editable table. Add your features, score them, and see the priority order.

Favicon Generator

Upload an image and generate all favicon sizes plus the HTML snippet you need — all client-side.

Embedding Similarity Calculator

Compare two texts using TF-IDF cosine similarity. See the similarity score, common terms, and unique terms for each input.

Email Subject Line Tester

Score your email subject lines on length, power words, personalization, urgency, spam triggers, and more.

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Docker Compose Validator

Paste your docker-compose.yml and validate services, ports, volumes, and structure against common mistakes.

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DNS Lookup

Query DNS records over HTTPS — A, AAAA, MX, TXT, CNAME, and NS — with TTL values and copy-friendly output.

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Diff Checker

Compare two texts side-by-side with color-highlighted line-by-line diff — all client-side.

Decision Matrix

Compare options against weighted criteria to find the best choice with a clear, visual ranking.

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CSV to JSON Converter

Upload or paste CSV data and instantly convert it to JSON with automatic type inference — all client-side.

CSS Grid Generator

Build CSS grid layouts visually — define columns, rows, gaps, and template areas, then copy the generated code.

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CSS Gradient Generator

Build linear, radial, and conic CSS gradients visually with color stops, angle controls, and instant code output.

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CSS Flexbox Playground

Configure CSS flexbox properties visually — see how flex containers and items behave with instant code output.

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CSP Header Builder

Build Content-Security-Policy headers interactively with directive explanations and live preview.

Cron Expression Builder

Build, parse, and preview cron expressions with visual selectors, human-readable descriptions, and next-run previews.

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CORS Checker

Test and validate CORS headers against your expected configuration — paste headers and verify policies.

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Conversion Rate Calculator

Track your marketing funnel from visitors to trials to paid customers with conversion rates, cost analysis, and a visual funnel.

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Contrast Ratio Checker

Check WCAG contrast ratios for text and background color combinations — see AA and AAA compliance at a glance.

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Color Converter

Convert colors between HEX, RGB, and HSL with a live preview swatch — all client-side.

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Cloud Cost Estimator

Compare approximate monthly and yearly compute, storage, and transfer costs across AWS, GCP, and Azure.

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Churn Rate Calculator

Calculate customer and revenue churn rates, visualize retention trends, and benchmark against SaaS industry standards.

Chunking Visualizer

Paste text and visualize how different chunking strategies split it. Compare fixed-size, sentence, paragraph, and recursive chunking with adjustable parameters.

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Changelog Generator

Paste conventional commits and generate a formatted changelog grouped by type.

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Business Name Generator

Generate creative business name ideas from your industry and keywords.

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Break-Even Calculator

Calculate your break-even point in units and revenue. See how fixed costs, variable costs, and price per unit affect profitability.

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Box Shadow Generator

Drag sliders to design box shadows visually and copy the CSS — supports multiple layers, inset, and spread.

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Blog Post Outline Builder

Generate structured blog post outlines with title variations, H2/H3 sections, intro, conclusion, and CTA.

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Base64 Encode/Decode

Encode and decode Base64 strings instantly — all client-side.

AWS Region Latency Tester

Measure approximate round-trip time to every AWS region from your browser and find the closest one.

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Aspect Ratio Calculator

Calculate width and height for any aspect ratio — perfect for responsive images, video embeds, and design layouts.

API Response Time Tester

Measure the response time of any public API endpoint from your browser.

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AI Cost Calculator

Estimate and compare API costs across GPT-4o, Claude 3.5 Sonnet, Gemini 1.5 Pro, and more. Calculate per-request, daily, monthly, and yearly spend.

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.env File Formatter

Sort, dedupe, lint, and clean your .env files. Catch unquoted values, duplicate keys, and exposed secrets.

Technical Debt Interest Calculator

Tech debt compounds like financial debt. See exactly what you're paying in interest — and when it's cheaper to refactor.

Square Texter

Type a word, see it rendered as a corner-square pattern. Instant, in-browser.