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AI Crawler Checker: See Exactly Which AI Bots Can Read Your Site
AI Crawler Checker audits your robots.txt and meta tags against GPTBot, ClaudeBot, CCBot, PerplexityBot and other AI crawlers, then hands you copy-paste blocking snippets.
Annuity Calculator Guide: Turn a Lump Sum Into Sustainable Monthly Withdrawals
The Annuity Calculator computes sustainable monthly withdrawals from a lump sum, with fixed or inflation-adjusted payouts, a depletion date, and total interest earned.
How to Convert ANSI Escape Codes to HTML: Render Terminal Logs with Perfect Colors
Turn raw ANSI escape codes into styled HTML with the ANSI to HTML Converter — colors, bold, italic, underline, strikethrough, 256-color, truecolor, dark or light live preview, fully client-side.
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AI Crawler Checker: See Exactly Which AI Bots Can Read Your Site
AI Crawler Checker audits your robots.txt and meta tags against GPTBot, ClaudeBot, CCBot, PerplexityBot and other AI crawlers, then hands you copy-paste blocking snippets.
Annuity Calculator Guide: Turn a Lump Sum Into Sustainable Monthly Withdrawals
The Annuity Calculator computes sustainable monthly withdrawals from a lump sum, with fixed or inflation-adjusted payouts, a depletion date, and total interest earned.
How to Convert ANSI Escape Codes to HTML: Render Terminal Logs with Perfect Colors
Turn raw ANSI escape codes into styled HTML with the ANSI to HTML Converter — colors, bold, italic, underline, strikethrough, 256-color, truecolor, dark or light live preview, fully client-side.
Audio Joiner: Merge Audio Files Online with Crossfade — No Upload Required
Learn how to merge multiple audio files into one seamless track with Audio Joiner, a free in-browser tool that adds crossfades or gaps — and never uploads your audio.
BAC Calculator: Estimate Your Blood Alcohol Content Over Time
Use the free BAC Calculator to estimate blood alcohol content over time with the Widmark formula, including time-to-zero projections and legal-limit thresholds.
Bicycle Gear Calculator: Gear Inches, Development and Gain Ratios Explained
Use the free Bicycle Gear Calculator to compute gear inches, development meters, gain ratios and speed at cadence from your chainring, cassette and wheel size — instantly in your browser.
Big Number Calculator: Exact Arithmetic Past Number.MAX_SAFE_INTEGER
The Big Number Calculator performs exact BigInt arithmetic on huge integers — factorials, powers, sums, products and floor division with remainder — entirely in your browser.
Board Foot Calculator: Price Your Lumber Before You Buy
Use the free Board Foot Calculator to compute board feet and total lumber cost for multiple plank sizes, complete with wood species price presets and a waste allowance.
Canal Boat Cost Calculator: Plan Your Narrowboat Budget Before You Buy
Use the free Canal Boat Cost Calculator to estimate annual narrowboat living costs — mooring, licence, insurance, diesel, pump-out, blacking, safety certificate and maintenance reserve — with a clear monthly breakdown.
Carton Capacity Calculator: Nail Items Per Carton and Cartons Per Container in Seconds
The Carton Capacity Calculator computes items per carton and cartons per pallet or container from your item and box dimensions, with orientation rotation and fill-ratio stats.
CLAUDE.md Generator: Build Project Context Files AI Agents Actually Read
CLAUDE.md Generator helps you build a CLAUDE.md project context file for AI coding agents from your repo commands, architecture notes, and team conventions — free, right in your browser.
How to Dial In Any Cup With a Coffee Brew Ratio Calculator
Learn how a coffee brew ratio calculator turns dose, water, and ratio into perfect pour-over, espresso, French press, and cold brew recipes — plus what each ratio actually tastes like.
Countertop Calculator: Estimate Slabs, Edges, and Kitchen Remodel Cost
The Countertop Calculator estimates slab count, edge-finishing length, and installed cost from your kitchen dimensions, with cutout deductions, waste allowance, and price presets built in.
CPU Flamegraph Visualizer: Turn Stack Traces Into an Interactive Flame Graph
CPU Flamegraph Visualizer renders perf script and py-spy output into an interactive SVG flame graph in your browser. Zoom into hot frames, search by name, and find CPU bottlenecks with no install.
Cron Gap Simulator: Catch Silent Gaps and Overlapping Jobs Before They Catch You
Cron Gap Simulator plots the next fire times of multiple cron expressions on one shared timeline, exposing silent gaps, overlapping runs, and timezone or DST surprises before they reach production.
CSS Masonry Generator: Build Pinterest-Style Masonry Layouts With Pure CSS
CSS Masonry Generator lets you visually build a true masonry layout with pure CSS and a multi-column fallback, complete with a live preview and copy-paste HTML and CSS output.
CSV Validator: Catch RFC 4180 Errors Before They Break Your Imports
Use CSV Validator to check any CSV file against RFC 4180 and catch ragged rows, unescaped quotes, BOM issues, and other csv errors before an import fails.
Decking Calculator: Estimate Boards, Joists and Screws Before You Build
Plan your deck with the free Decking Calculator — estimate deck boards, joists and screws from your deck dimensions, with waste allowance and cost totals, all client-side.
Duplicate File Finder: Reclaim Wasted Space with SHA-256 Exact Matching
The Duplicate File Finder compares files by SHA-256 hash, groups true duplicates, and suggests which copies to keep or delete — entirely in your browser, with nothing uploaded.
EML Header Viewer: Read Email Headers Like a Security Investigator
Use the EML Header Viewer to open .eml files in your browser and inspect headers, SPF/DKIM/DMARC verdicts, Reply-To mismatches, and the Received chain - with no upload required.
How to Read EPUB Books in Your Browser — No App Required
EPUB Reader lets you open and read e-books directly in your browser, with chapter browsing, adjustable typography, and text extraction — fully offline, with no upload needed.
Fence Calculator: Plan Posts, Pickets and Costs Before You Dig
The free Fence Calculator turns your perimeter length, gates and picket dimensions into exact fence posts, rails, pickets, concrete bag estimates and full cost totals — instantly, right in your browser.
File Encoding Detector: Fix Mojibake and Convert Any Text File to UTF-8
See mojibake instead of text? File Encoding Detector identifies the true encoding of any text file — UTF-8, UTF-16, Shift-JIS, TIS-620 — and converts it cleanly to UTF-8, entirely in your browser.
How to Encrypt Files Online Safely: A Complete Guide to Browser-Based AES-256 Encryption
File Encryptor locks down any file with AES-256-GCM entirely inside your browser — encrypt with a passphrase, verify the round trip, and never upload a single byte.
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Last updated: December 7, 2025