Free Utilities & Developer Tools
Ultra-fast, browser-based calculators and engineering tools built for designers, video editors, frontend developers, and content creators. Privacy-first with zero tracking of your inputs.
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ChatGPT Ad Blocker
Block ChatGPT upgrade banners, upsell promo cards, and partner app ads with a lightweight, privacy-first Manifest V3 Chrome extension.
JSON diff
JSON diff. Use this privacy-first json diff directly in your browser.
Base64 encoder
Base64 encoder. Use this privacy-first base64 encoder directly in your browser.
URL parser
URL parser. Use this privacy-first url parser directly in your browser.
JWT debugger
JWT debugger. Use this privacy-first jwt debugger directly in your browser.
UUID generator
UUID generator. Use this privacy-first uuid generator directly in your browser.
Embedding inspector
Inspect AI embedding vectors — compute L2 norm, cosine similarity, dot product, and dimension statistics. Runs fully in your browser.
Word counter
Word counter. Use this privacy-first word counter directly in your browser.
Case converter
Case converter. Use this privacy-first case converter directly in your browser.
Duplicate remover
Duplicate remover. Use this privacy-first duplicate remover directly in your browser.
Slug generator
Slug generator. Use this privacy-first slug generator directly in your browser.
Text diff
Text diff. Use this privacy-first text diff directly in your browser.
SERP Preview
Simulate desktop and mobile Google Search result snippets in real-time.
Robots Tester
Test robots.txt directives and Googlebot / AI crawler accessibility.
Canonical Checker
Audit canonical link tags and eliminate duplicate content issues.
Schema Validator
Validate JSON-LD structured data and Schema.org syntax.
Redirect Chain Checker
Trace multi-hop 301 and 302 HTTP redirect chains.
SEO Checker
Audit on-page SEO quality, heading hierarchy, and meta tag completeness.
CAC payback
CAC payback. Use this privacy-first cac payback directly in your browser.
Chapter formatter
Chapter formatter. Use this privacy-first chapter formatter directly in your browser.
Bio formatter
Bio formatter. Use this privacy-first bio formatter directly in your browser.
Eval rubric generator
Eval rubric generator. Use this privacy-first eval rubric generator directly in your browser.
Rate Limit Planner
Generate production-ready Exponential Backoff code snippets based on custom RPM and TPM limits.
JSON path finder
JSON path finder. Use this privacy-first json path finder directly in your browser.
JSON repair
JSON repair. Use this privacy-first json repair directly in your browser.
XPath tester
XPath tester. Use this privacy-first xpath tester directly in your browser.
CSV validator
CSV validator. Use this privacy-first csv validator directly in your browser.
Delimiter converter
Delimiter converter. Use this privacy-first delimiter converter directly in your browser.
Column extractor
Column extractor. Use this privacy-first column extractor directly in your browser.
CSV deduper
Remove duplicate rows from CSV files instantly in your browser. Paste your CSV data and get a clean, deduplicated output with a deduplication report.
Escape helper
Escape special characters for HTML, JavaScript strings, and URL encoding. Instantly see HTML entity escaping, JS string escaping, and percent-encoding side by side.
JWT inspector
JWT inspector. Use this privacy-first jwt inspector directly in your browser.
Dockerfile linter
Lint your Dockerfile for common mistakes and best-practice violations. Detects missing WORKDIR, untagged base images, absent EXPOSE instructions, and more.
Cron explainer
Cron explainer. Use this privacy-first cron explainer directly in your browser.
Env diff
Env diff. Use this privacy-first env diff directly in your browser.
Changelog formatter
Changelog formatter. Use this privacy-first changelog formatter directly in your browser.
Compound interest
Compound interest. Use this privacy-first compound interest directly in your browser.
Average calculator
Average calculator. Use this privacy-first average calculator directly in your browser.
Date difference
Date difference. Use this privacy-first date difference directly in your browser.
CLS checklist
CLS checklist. Use this privacy-first cls checklist directly in your browser.
Checklist builder
Checklist builder. Use this privacy-first checklist builder directly in your browser.
Reading time calculator
Reading time calculator. Use this privacy-first reading time calculator directly in your browser.
Citation formatter
Citation formatter. Use this privacy-first citation formatter directly in your browser.
Column profiler
Column profiler. Use this privacy-first column profiler directly in your browser.
Color scale generator
Generate a Tailwind-style color palette from any hex color. Enter a base hex value and get a full 10-step shade scale from 50 to 900. Runs in your browser.
cURL builder
Build a complete cURL command from a human-readable request spec. Paste method, URL, headers, and body — get a ready-to-run curl command. Fully local.
16 9 Dimensions Calculator
Browser native 16 9 Dimensions Calculator utility.
9 16 Dimensions Calculator
Browser native 9 16 Dimensions Calculator utility.
Aspect Ratio Calculator
Browser native Aspect Ratio Calculator utility.
Color Contrast Checker
Browser native Color Contrast Checker utility.
Css Clamp Calculator
Browser native Css Clamp Calculator utility.
Csv To Json
Browser native Csv To Json utility.
Dpi Print Size Calculator
Browser native Dpi Print Size Calculator utility.
Json Formatter
Browser native Json Formatter utility.
Json Minifier
Browser native Json Minifier utility.
Json To Typescript
Browser native Json To Typescript utility.
Json To Xml
Browser native Json To Xml utility.
Json Validator
Browser native Json Validator utility.
Megapixels To Resolution Calculator
Browser native Megapixels To Resolution Calculator utility.
Meta Tag Analyzer
Browser native Meta Tag Analyzer utility.
Opportunity Radar
Browser native Opportunity Radar utility.
Percentage Difference Calculator
Browser native Percentage Difference Calculator utility.
Pixels To Megapixels Calculator
Browser native Pixels To Megapixels Calculator utility.
Ppi Calculator
Browser native Ppi Calculator utility.
Profit Margin Calculator
Browser native Profit Margin Calculator utility.
Px To Rem
Browser native Px To Rem utility.
Resize Dimensions Calculator
Browser native Resize Dimensions Calculator utility.
Schema Generator
Browser native Schema Generator utility.
Sitemap Validator
Browser native Sitemap Validator utility.
Social Media Image Sizes
Browser native Social Media Image Sizes utility.
Svg To Jsx
Browser native Svg To Jsx utility.
Xml Formatter
Browser native Xml Formatter utility.
Yaml To Json
Browser native Yaml To Json utility.
Youtube Video Size Calculator
Browser native Youtube Video Size Calculator utility.
AI Prompt Optimizer
Optimize AI system prompts with explicit roles, context variables, and structured output rules.
Multi-Persona AI Prompt Generator
Generate structured system prompts across software engineering, SEO, and product management personas.
AI Text Perplexity & Burstiness Checker
Audit text for AI generation patterns using sentence burstiness metrics and vocabulary perplexity proxies.
LLM BPE Tokenizer & Multi-Model Counter
Count tokens across GPT-4o, Claude 3.5 Sonnet, and Llama 3 models.
RAG Retrieval Precision & Recall Evaluator
Audit RAG retrieval quality: calculate Precision@K, Recall@K, F1 Score, and Context Noise Ratio.
JSON Schema Validator & Output Auditor
Validate JSON payloads against JSON Schema Draft 7 and 2020-12 standards.
OpenAI GPT-4o & O3-Mini API Cost Estimator
Calculate API pricing for OpenAI GPT-4o, GPT-4o-mini, O3-mini, and O1 models.
Anthropic Claude 3.5 Sonnet Cost Estimator
Calculate API pricing for Anthropic Claude 3.5 Sonnet, Haiku, and Opus models.
Google Gemini 1.5 Pro & Flash Cost Estimator
Calculate API pricing for Google Gemini 1.5 Pro, Flash, and 2.0 Flash models.
Content Security Policy (CSP) Header Generator
Generate Content-Security-Policy HTTP headers to block XSS and unauthorized script execution.
HTTP Strict Transport Security (HSTS) Generator
Generate HTTP Strict-Transport-Security headers and qualify for HSTS preload submission.
X-Frame-Options Clickjacking Protection Generator
Generate X-Frame-Options DENY and SAMEORIGIN HTTP headers to prevent clickjacking.
CORS Access-Control Header Generator
Generate Access-Control-Allow-Origin, Methods, and Headers for API endpoints.
JWT Token Generator & Base64URL Encoder
Generate and encode JSON Web Tokens (JWT) with HS256 HMAC signatures client-side.
Time-Ordered UUID v7 Generator
Generate time-ordered RFC 9562 UUID v7 primary keys for database B-Tree index optimization.
SQL Query Formatter & Prettifier
Format and prettify SQL queries for PostgreSQL, MySQL, and BigQuery client-side.
HTML to Markdown Converter
Convert HTML markup into clean GitHub Flavored Markdown (GFM) text.
Markdown to HTML Converter
Convert GitHub Flavored Markdown (GFM) text into clean HTML5 markup.
HTML5 Canvas QR Code Generator
Generate high-resolution QR codes client-side with PNG download.
JSON Repair & Malformed Syntax Fixer
Repair malformed JSON strings, single quotes, trailing commas, and unquoted keys.
JSONPath Evaluator & Key Extractor
Evaluate JSONPath expressions against nested JSON payloads client-side.
Cron Expression Generator & Explainer
Translate 5-part cron expressions into plain English and view next run schedules.
Base64 Text & Data URL Encoder / Decoder
Encode and decode text strings and binary file Data URLs to Base64 format.
String Case Converter (camelCase, snake_case)
Convert text strings to camelCase, snake_case, kebab-case, PascalCase, and CONSTANT_CASE.
URL-Friendly Slug Generator
Generate clean, URL-safe slugs for blog titles, products, and landing pages.
XML to JSON Converter
Convert XML documents into clean, structured JSON objects client-side.
LLM GPU VRAM Memory Requirement Calculator
Calculate GPU VRAM memory requirements for running LLMs locally or in cloud deployments.
Vector Embedding Cosine Similarity Calculator
Calculate cosine similarity, dot product, and Euclidean distance between 2 vector embeddings.
JSON to CSV Converter
Convert JSON object arrays into clean CSV spreadsheets client-side.
YAML Syntax Validator & Linter
Validate YAML code syntax, lint space indentation, and detect unescaped strings.
Date Difference & Business Days Calculator
Calculate calendar days, weeks, and working business days between two dates.
Compound Interest & Investment Growth Calculator
Calculate compound interest growth, annual compounding returns, and recurring monthly deposits.
SaaS CAC Payback Period & LTV Calculator
Calculate SaaS Customer Acquisition Cost (CAC) payback period in months and LTV:CAC ratios.
CSV / TSV / Pipe Delimiter Converter
Convert tabular data between Comma (CSV), Tab (TSV), Pipe (|), and Semicolon (;) delimiters.
CSV Column Extractor & Filter
Extract specific columns from CSV datasets, reorder fields, and drop unwanted columns client-side.
Cumulative Layout Shift (CLS) Audit & Fix Checklist
Audit Web Vitals Cumulative Layout Shift (CLS) score and apply CSS width/height fixes.
CSV to Excel XLSX & TSV Converter
Convert CSV files into Excel-compatible TSV spreadsheets and export table files client-side.
Excel to CSV Converter
Convert Excel TSV clipboard data and spreadsheets into clean, standardized CSV files client-side.
Windows EVTX to CSV / TXT Converter & Log Viewer
Parse Windows Event Log (.evtx, .xml, .txt) files client-side and export to CSV, TXT, or JSON.
SVG to PNG Converter & Vector Exporter
Convert SVG vector graphics and code into high-resolution PNG image files client-side.
WebP to PNG Converter
Convert WebP images into lossless PNG files client-side preserving image transparency.
JSON to YAML Converter & Config Builder
Convert JSON object structures into clean, 2-space indented YAML files client-side.
PNG to WebP Converter & Image Compressor
Convert PNG images into lightweight WebP format client-side with quality sliders.
Regex Pattern Tester & Match Explainer
Test Regular Expressions (Regex) against text client-side with match highlighting and capture group tables.
Markdown Table Generator & Prettifier
Build, format, and align GitHub Flavored Markdown (GFM) tables client-side.
Base64 Image Converter & Data URL Encoder
Convert images into Base64 Data URL strings client-side for HTML/CSS embedding.
CSS Flexbox Layout Generator & Visual Builder
Build and preview CSS Flexbox layouts interactively with live alignment and gap controls.
CSS Grid Layout Generator & Visual Builder
Build and preview 2D CSS Grid layouts interactively with track size and gap controls.
HTTP Request & Response Header Inspector
Inspect, parse, and analyze HTTP request and response headers client-side with security header scoring.
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Tool Guides & In-Depth Technical Reviews
Bilibili Translator: Real-Time Universal In-Place Translation in All Languages | Nadhebe
Translate Bilibili into any language in real time across all browsers. Features in-place DOM replacement, 0ms local dictionaries, and Danmaku isolation.
Claude 3.7 Sonnet Hybrid Reasoning: When to Use Thinking Tokens vs Standard Fast Mode
Master Claude 3.7 Sonnet's hybrid reasoning architecture. Learn how to configure dynamic thinking budgets, benchmark against o3-mini, and optimize API costs.
Speculative Decoding in vLLM & SGLang: 3x LLM Inference Speedup Guide
Accelerate LLM inference throughput and reduce latency by up to 3x using speculative decoding, draft models, and Medusa heads in vLLM and SGLang.
Google AI Studio System Prompts & Structured Outputs Architecture Guide
A comprehensive guide on configuring system instructions, JSON Schema structured outputs, function calling, and temperature parameters in Google AI Studio for production AI applications.
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