Most of the work these tools handle — parsing a cron expression, projecting a mortgage, generating a key pair, formatting a JSON payload — does not warrant a sign-up flow, a desktop install, or a recurring charge. So we built a collection of small, precise utilities that do the work in a browser tab and get out of the way. Every tool computes locally; nothing about your inputs reaches a server. The cryptography uses the platform Web Crypto API. The financial models include the second-order effects competitors leave out — opportunity cost, inflation, amortisation against principal. Outputs flow between compatible tools through a single Send-to button, every scenario is shareable as a plain URL, and every recent input is one click away. The same code runs identically on a phone and a workstation.

Twenty hand-translated languages Outputs flow between tools Computation stays on your device Backed by the Web Crypto API Identical on desktop and mobile No sign-up, no install

starA closer look at five tools

A small selection from across the categories — picked because each addresses a problem where the easily findable alternatives tend to be either over-simplified or buried inside larger paid products.

Privacy-first vpn_keyAsymmetric Key Generator

RSA, ECDSA, and Ed25519 key pairs generated by the Web Crypto API. The private half is produced and stays on your device — the only place it should ever exist before you choose to save it.

 Finance real_estate_agentBuy vs Rent Calculator

A full opportunity-cost model that compares ownership and renting year by year, factoring down-payment investment returns, rent growth, appreciation, and inflation. Charts and amortisation tables export cleanly to PNG, CSV, or JSON.

 Developer text_formatVariable Naming Converter

Convert any identifier or phrase to camelCase, PascalCase, snake_case, kebab-case, SCREAMING_SNAKE_CASE, and several less common conventions, all in a single pass.

 Developer timerCron Expression Parser

Translate a cron expression into plain English and the next five scheduled runs. A quick sanity check before a job ships into production scheduling.

 Privacy-first keySymmetric Key Generator

AES and HMAC keys at every standard length, drawn from the same cryptographically secure entropy source TLS uses. Output in hex, Base64, or raw bytes.

paymentsMoney

real_estate_agentBuy vs Rent Calculator Compare buying a home versus renting and investing the difference currency_exchangeCurrency Converter Convert between world currencies with live rates trending_upInvestment Calculator See how your money grows over time with compound interest account_balanceLoan Calculator Monthly payment, total interest, and amortization schedule houseMortgage Calculator Monthly payment, total interest, and year-by-year amortization elderlyRetirement / FIRE Calculator Plan retirement with compound growth, inflation, and the 4% rule savingsSavings Goal Calculator Plan how to reach your savings goal over time

codeDevelopment

enhanced_encryptionAES Text Encryption Encrypt and decrypt text with AES-256-GCM and a password vpn_keyAsymmetric Key Generator Generate RSA or EC key pairs in PEM format swap_horizBase64 Encoder/Decoder Encode text to Base64 or decode Base64 back to text paletteColor Converter Convert between HEX, RGB, and HSL with live preview timerCron Expression Parser Parse cron expressions into plain English differenceDiff Checker Compare two texts and highlight the differences fingerprintHash Calculator Calculate SHA-256, SHA-384, SHA-512, SHA-1, or MD5 hashes data_objectJSON Formatter Format, minify, sort keys, stringify, and destringify JSON verified_userJWT Decoder & Verifier Decode JWT header and payload, verify the signature client-side manage_searchRegex Tester Test regular expressions with match highlighting and capture groups format_list_numberedSequence Generator Generate numeric sequences with custom prefix, suffix, and separator keySymmetric Key Generator Generate random AES keys in hex, Base64, or raw bytes scheduleUnix Timestamp Converter Convert between Unix timestamps and human-readable dates linkURL Encoder/Decoder Encode or decode URL components tagUUID Generator Generate random UUIDs (v4) in bulk text_formatVariable Naming Converter Convert text between camelCase, snake_case, kebab-case, PascalCase, and more sync_altYAML / JSON Converter Convert between YAML and JSON formats

casinoRandom

monetization_onCoin Flip Flip a coin one or more times casinoDice Roller Roll dice of any type with statistics reorderList Randomizer Shuffle any list instantly pinRandom Number Generator Generate random numbers within a range shuffleRandom Picker Pick one or more random items from a list

handymanEveryday

monitor_weightBMI Calculator Calculate Body Mass Index with health categories contrastColor Contrast Checker Check WCAG AA/AAA color contrast for accessibility hourglass_emptyCountdown Timer Count down to any date with live updating passwordPassword Generator Generate strong, random passwords picture_as_pdfPDF Toolkit Merge, split, and rotate PDFs privately in your browser percentPercentage Calculator Calculate percentages, ratios, and percentage changes qr_codeQR Code Generator Create QR codes from text or URLs menu_bookText Readability Analyzer Score text with Flesch, Flesch-Kincaid, Gunning Fog, SMOG, and more text_fieldsWord & Character Counter Count words, characters, sentences, and estimate reading time

helpQuestions, answered

What the site is, how it handles your data, and what you can rely on it for.

Are these tools really free?
Yes — every tool is free for personal and commercial use, with no account, no trial, and no paywalled features. The site is funded by unobtrusive advertising rather than by selling data.
Does any of my data leave my device?
No. Every tool runs entirely inside your browser, so the text you paste, the files you open, and the keys you generate are processed locally and are never uploaded, stored, or logged.
Do I need to install anything or sign up?
Nothing to install and nothing to sign up for. Open the page and the tool is ready in any modern browser, on desktop, tablet, or phone.
Do the tools work the same on mobile?
Yes. Every tool is built mobile-first and behaves identically on a phone and a workstation — the same features, the same layout logic, and the same precision.
Which languages are available?
Twenty, each reviewed by a person rather than machine-translated. Switch between them at any time from the language selector in the header.
Can I rely on the calculators for financial decisions?
They are carefully built models meant for planning and comparison, but they are informational tools, not professional advice. For decisions with real money at stake, confirm the numbers with a qualified advisor.
How is the cryptography handled?
Keys, hashes, and encryption use the browser's built-in Web Crypto API — the same audited primitives that protect HTTPS — so the algorithms and randomness meet platform security standards without any third-party library.

rocket_launchMaintained, extended, and open to requests

New tools ship on a regular cadence and existing ones are revised as the standards beneath them evolve — RFC updates, new CSS colour spaces, fresh signature algorithms. The decision of what ships next is shaped by what people actually ask for; the contact address below is the inbox the maintainer reads.

add_circleRequest a tool

Tools run entirely on your device. Inputs are not transmitted, stored, or logged.