# ToolUpKit > Free online calculators and developer tools that run entirely in your browser. No signup, no upload, no stored data. A zero-backend, fully static online tool matrix. Every tool runs locally in the browser — nothing is uploaded or stored. The catalogue is organised as domain → category → tool. ## Data & Format Formatting, validation and conversion for structured data such as JSON, YAML, XML, CSV and TOML. ### JSON Tools - [JSON Formatter](https://www.toolupkit.com/json/json-formatter/): Paste JSON to pretty-print it with consistent indentation, minify it to one line, or find the exact line and column of a syntax error. Runs locally. - [JSON Diff](https://www.toolupkit.com/json/json-diff/): Compare two JSON documents and see every added, removed and changed value, with the JSON path of each difference and a one-click copy. - [JSON to CSV](https://www.toolupkit.com/json/json-csv/): Convert JSON to CSV with a documented rule for flattening nested objects and arrays, plus a round-trip check that shows what the reverse conversion loses. - [JSON to YAML](https://www.toolupkit.com/json/json-yaml/): Convert JSON to YAML and YAML to JSON in your browser, with a clear note on what the round trip loses: comments, anchors, multiple documents and key order. - [JSON Schema Validator](https://www.toolupkit.com/json/json-schema/): Validate a JSON document against a JSON Schema and get every error with its exact path, including failures nested inside objects and array items. Runs locally. - [JSON to XML](https://www.toolupkit.com/json/json-xml/): Convert JSON to XML and XML to JSON with the array mapping rules spelled out, so the output matches what your downstream consumer expects. - [JSONPath Tester](https://www.toolupkit.com/json/jsonpath/): Run a JSONPath expression against your own JSON and get every match together with the path that reached it. Filter, slice and search without writing code. - [JSON to TOML Converter](https://www.toolupkit.com/json/json-toml/): Convert JSON to TOML and TOML to JSON, with a clear choice for how null values are handled, since TOML has no null. Runs locally. ## Text & Encoding Word counts, character checks and other text statistics for writers and editors. ### Text Tools - [Word Counter](https://www.toolupkit.com/text/word-counter/): Count words, characters and paragraphs as you type, and check the result against social platform and meta description limits. Runs entirely in your browser. ## Calculation & Conversion Loan, money and unit calculators for everyday decisions. ### Calculators - [Extra Payment Mortgage Calculator](https://www.toolupkit.com/calculator/mortgage-calculator/): See how extra monthly or one-off payments shorten a mortgage and how much interest they remove, with a month-by-month schedule. Runs locally. - [Car Insurance Comparison Calculator](https://www.toolupkit.com/calculator/car-insurance-calculator/): Compare car insurance quotes side by side: annual premium, deductible, and the out-of-pocket cost before cover starts. See the real yearly cost. - [Personal Injury Settlement Calculator](https://www.toolupkit.com/calculator/personal-injury-calculator/): Estimate what a personal injury claim may be worth from medical costs, lost earnings and pain and suffering, with liability and policy limits applied. - [Life Insurance Needs Calculator](https://www.toolupkit.com/calculator/life-insurance-calculator/): Work out how much life insurance your household actually needs to replace income and clear debts, and see the gap with the cover you already hold. - [Credit Card Payoff Calculator](https://www.toolupkit.com/calculator/credit-card-payoff-calculator/): See how long it takes to clear your card balances and what the interest costs. Compare the avalanche and snowball methods with your own rates. - [Retirement Savings Calculator](https://www.toolupkit.com/calculator/retirement-calculator/): See what your savings become by retirement, the monthly income they support, how that compares with the 4% rule, and what Social Security covers. - [Student Loan Repayment Calculator](https://www.toolupkit.com/calculator/student-loan-calculator/): Compare every federal repayment plan side by side: monthly payment, total interest, how long it runs, what gets forgiven and the tax bill that comes with it. - [Home Equity Loan Calculator](https://www.toolupkit.com/calculator/home-equity-calculator/): Work out how much you could borrow against your home: your equity, the loan-to-value ceiling and the monthly payment on a HELOC or home equity loan. - [Rent vs Buy Calculator](https://www.toolupkit.com/calculator/rent-vs-buy-calculator/): Compare renting with buying the same home over the same period — mortgage, taxes, maintenance, opportunity cost — and find your break-even year. - [Debt Consolidation Calculator](https://www.toolupkit.com/calculator/debt-consolidation-calculator/): See whether folding card balances into one loan saves money: compare the blended card rate with the loan rate, and weigh term against interest. - [ROI Calculator](https://www.toolupkit.com/calculator/roi-calculator/): The return on an investment in three ways: total return, the annualized rate solved from your exact cash flows, and a benchmark comparison. ### Converters - [Currency Converter](https://www.toolupkit.com/converter/currency-converter/): Convert between 162 currencies at the mid-market rate, with the inverse rate, a typical bank spread, and the quote date and source shown. - [Unit Converter](https://www.toolupkit.com/converter/unit-converter/): Convert length, weight, temperature, area, volume, speed, data and time as you type, computed from the exact international definitions. ## Web & Network URL, query string, HTTP and front-end debugging tools. ### Generators - [WiFi QR Code Generator](https://www.toolupkit.com/generator/wifi-qr-code-generator/): Turn a network name and password into a scannable WiFi QR code. Pick WPA, WPA2, WEP or an open network, then download a PNG or SVG. ## Images & Media Image compression, format conversion and media processing tools. ### Design & Icons - [Favicon Generator](https://www.toolupkit.com/design/favicon-generator/): Generate a favicon.ico plus 16, 32, 64 and 128 px PNG icons from a letter, initials or an image. Preview them in a real browser tab, then download the set. - [CSS Gradient Generator](https://www.toolupkit.com/design/css-gradient-generator/): Build a CSS linear or radial gradient visually: place colour stops, set the angle, alpha and position, then copy the CSS or a Tailwind class. - [Color Palette Generator](https://www.toolupkit.com/design/color-palette-generator/): Type a base colour to get complementary, analogous, triadic or monochrome schemes. Every swatch shows HEX, RGB and HSL — copy any value in one click. ### Image Tools - [Image Format Converter](https://www.toolupkit.com/image/image-converter/): Batch-convert images between JPG, PNG, WebP and AVIF in your browser. Drag in a folder, set a quality level, and download a ZIP — nothing is uploaded. ## Date & Time Timestamp, timezone and date calculation tools. ### Date & Time Tools - [Unix Timestamp Converter](https://www.toolupkit.com/time/timestamp-converter/): Convert Unix timestamps to readable dates and dates back to epoch. The unit is detected automatically and every time zone is shown side by side. ## Encoding & Escaping Escape, unescape and encode text and structured data — JSON string escaping, Base64 and character encoding, all in your browser. ### Encoding & Escaping - [Query String to JSON](https://www.toolupkit.com/encoding/query-json/): Convert a URL query string to JSON and back, preserving repeated keys as arrays and showing how plus signs and percent-encoding differ. Runs locally. - [JSON Escape and Unescape](https://www.toolupkit.com/encoding/json-escape/): Escape text into a valid JSON string literal and unescape it back, and see why hand-writing escapes breaks on control characters. Runs locally. - [Base64 in JSON](https://www.toolupkit.com/encoding/json-base64/): Encode and decode Base64 in the browser, including URL-safe Base64 and the payload section of a JWT. Runs locally; Base64 is encoding, not encryption. ## Documents & Files Merge, split and rearrange PDF documents in your browser — the file is read locally and never uploaded. ### PDF Tools - [PDF Merger & Splitter](https://www.toolupkit.com/pdf/pdf-merger/): Merge several PDFs into one document, or split a PDF into separate files by page range or fixed chunks. Every page is copied in your browser and never uploaded. ## Security & Privacy Generate and check credentials, and other privacy-first tools that run entirely in your browser. ### Security Tools - [Password Generator](https://www.toolupkit.com/security/password-generator/): Create strong random passwords in your browser. Set length and character types, exclude look-alikes, and generate many at once. Nothing is uploaded or stored. ## Index - Sitemap: https://www.toolupkit.com/sitemap-index.xml - Full reference (every tool expanded: how it works, sources, FAQ): https://www.toolupkit.com/llms-full.txt