Free Online Converters

A hosted suite of browser converters — convert images between PNG, JPG, WEBP, GIF and BMP, change text case, convert units of measurement, translate colors across HEX, RGB and HSL, spell out any number in words, convert military time with a full 24-hour chart, and convert 160+ currencies with live exchange rates. No installs, no sign-up, results as you type.

The tools fall into five families: image formats (including HEIC to JPG and WebP to PNG); developer data — CSV to JSON, JSON to CSV, XML to JSON and Excel to CSV; text and numbers; measurement and color; and time and date. Every conversion runs entirely in your browser, so nothing you upload leaves your device.

Free

Image Converter

Convert any image between PNG, JPG, WEBP, GIF and BMP — every combination. Drag in a file, pick a format, set quality for JPG and WEBP, and download. Nothing is uploaded.

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Case Converter

Convert text to UPPERCASE, lowercase, Title Case, Sentence case or tOGGLE cASE — with live character, word and line counts and one-click copy.

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CSV to JSON Converter

Convert CSV to JSON in your browser — an array of objects or arrays, with header detection, delimiter auto-detect and number parsing. Nothing uploaded.

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JSON to CSV Converter

Convert JSON to CSV in your browser — an array of objects or arrays becomes a clean table, with a header row and delimiter options. Nothing uploaded.

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XML to JSON Converter

Convert XML to JSON in your browser — nested elements become objects, repeated tags become arrays, attributes optional. Nothing uploaded.

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JSON to XML Converter

Convert JSON to XML in your browser — objects become nested elements, arrays repeat tags, and @keys become attributes. Pretty-print and download. Nothing uploaded.

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JSON to YAML Converter

Convert JSON to readable YAML in your browser — pick 2- or 4-space indent, optionally sort keys, then copy or download. Nothing uploaded.

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YAML to JSON Converter

Convert YAML to JSON in your browser — mappings become objects, sequences become arrays, pretty-printed or minified. Nothing uploaded.

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Excel to CSV Converter

Convert Excel to CSV in your browser — open an .xlsx or .xls file, pick a sheet, choose a delimiter and download. Nothing uploaded.

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CSV to Excel Converter

Convert CSV to a real .xlsx workbook in your browser — paste or load a file, preview the table, and download. Delimiter auto-detect. Nothing uploaded.

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Unit Converter

Convert length, weight, temperature, volume and speed between metric and imperial units in real time, with a swap button and exact conversion factors.

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Color Converter

Convert a color between HEX, RGB and HSL with a live preview swatch and a native color picker. Edit any format and the others update instantly.

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Currency Converter

Convert between 160+ world currencies with live mid-market exchange rates, updated daily. Pick two currencies, type an amount, and swap.

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Numbers to Words Converter

Spell out any number in English — plain words, check-writing dollar amounts or ordinals like twenty-first — up to the vigintillions, with one-click copy.

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Military Time Converter

Convert military time to regular time and back instantly, see the current military time live, and look any hour up in the full 24-hour chart.

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Julian Date Converter

Convert a date to the ordinal Julian date (the day-of-year code like 26206) or the astronomical Julian Day (JD, JDN, MJD) — and back. Two formats, both directions.

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Roman Numeral Converter

Convert numbers to Roman numerals and back, plus turn a date into Roman numerals.

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Cooking & Baking Converter

Convert cups, grams, tablespoons, ounces and milliliters for any ingredient, with King Arthur-cited baking weights for flour, sugar and butter.

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How Converters Works

Sixteen focused tools, one consistent interface. Pick a converter, add your input, and get the result instantly.

1

Pick a converter

Choose the Image Converter for picture formats, the developer data converters — CSV to JSON, JSON to CSV, XML to JSON, JSON to XML, Excel to CSV and CSV to Excel — for structured files, the Case Converter for text, the Unit Converter for measurements, the Color Converter for design values, the Numbers to Words Converter to spell out a number, the Military Time Converter for 24-hour time and its chart, the Julian Date Converter for day-of-year and astronomical Julian Day codes, the Roman Numeral Converter to convert between numbers and Roman numerals, the Cooking & Baking Converter for ingredient-aware kitchen measures, or the Currency Converter for live exchange rates. Each one is a single page with one job.

2

Enter a value

Type or paste your text, number, or color. Conversion happens live as you type — there is no convert button to wait on, and nothing is sent to a server.

3

Copy the result

Copy the converted output to your clipboard with one tap. Everything runs in your browser, so the tools stay fast and private and keep working offline once loaded.

Frequently Asked Questions

What are the LK Forge Converters?
Converters is a free suite of browser-based conversion tools hosted on LK Forge. It currently includes an Image Converter that converts pictures between PNG, JPG, WEBP, GIF and BMP, a Case Converter that changes text between UPPERCASE, lowercase, Title Case, Sentence case and tOGGLE cASE, a Unit Converter that handles length, weight, temperature, volume and speed with a swap button and live results, a Color Converter that converts a color between HEX, RGB and HSL with a live preview swatch, a Numbers to Words Converter that spells out any number in English words including check-writing dollar amounts and ordinals, a Military Time Converter that converts military time to regular 12-hour time both ways with a full 24-hour chart, a Currency Converter that converts between 160+ world currencies using live mid-market exchange rates updated daily, and a Roman Numeral Converter that converts numbers to Roman numerals and Roman numerals back to numbers, plus a date-to-Roman mode. The conversions run in your browser — nothing you provide is uploaded or stored, and there is no sign-up. The image, case, unit, color, numbers-to-words, military-time and roman-numerals tools work fully offline; the currency converter only downloads the public exchange-rate table.
Are the converters free and private?
Yes. Every tool in the suite is completely free with no account, no payment, and no usage cap. Because all of the conversion math runs client-side in JavaScript, the text, numbers, and colors you enter never leave your device — there are no server round-trips and nothing is logged. That makes the tools safe to use for sensitive text and fast enough to update on every keystroke, even offline once the page has loaded.
Do I need to install anything?
No. There is nothing to download and no extension to add. The converters work in any modern browser on desktop, tablet or mobile. Open a tool, paste or type a value, and read the result — they are a quick, hosted alternative to spreadsheet formulas, command-line scripts, or design-app color pickers when you just need a fast one-off conversion.
How accurate are the unit and color conversions?
Unit conversions use exact internationally defined factors — for example one inch is exactly 0.0254 meters and one pound is exactly 0.45359237 kilograms — and results are shown to eight significant figures, then trimmed of trailing zeros. Temperature uses the precise Celsius, Fahrenheit and Kelvin formulas rather than approximations. Color conversions use the standard sRGB and HSL math, so a value round-trips cleanly between HEX, RGB and HSL.
What is the difference between CSV and JSON, and which should I use?
CSV is a flat table — rows and columns separated by commas — so it is compact and opens directly in Excel, Google Sheets or any database import. JSON is a nested, typed structure of objects and arrays, which is what most web APIs and config files expect. Use CSV for spreadsheets and bulk data; use JSON for anything a program will read. To move between them, the CSV to JSON converter turns a table into an array of objects with header detection and number parsing, and the JSON to CSV converter flattens objects back into a clean table — both entirely in your browser.
How do I convert nested JSON to a CSV spreadsheet?
Paste your JSON into the JSON to CSV converter. An array of objects becomes rows with a header row built from the keys; nested objects and arrays are serialised into single cells so nothing is lost, and you can pick the delimiter (comma, semicolon or tab) to match your locale before downloading. If your data starts as an Excel file, run it through Excel to CSV first, or go the other way with CSV to Excel to get a real .xlsx workbook.
Should I convert my images to PNG, JPG or WEBP?
Use JPG for photographs where small file size matters and a little compression is fine; use PNG when you need sharp edges, text or transparency with no quality loss; use WEBP to get PNG-quality transparency at roughly JPG file sizes for the web. The Image Converter handles every combination of PNG, JPG, WEBP, GIF and BMP, with a quality slider for JPG and WEBP — and, like the rest of the suite, it never uploads your file.
How do I convert HEIC iPhone photos to JPG?
iPhones save photos in Apple's HEIC format, which many websites and Windows apps cannot open. Open the HEIC to JPG converter, drop in one or more .heic files, and download standard JPGs — the decode runs locally in your browser, so the photos never leave your device. For web use you can instead convert to WEBP with the Image Converter.
How do I turn an Excel spreadsheet into CSV or JSON?
Use Excel to CSV to open an .xlsx or .xls file, pick the sheet and delimiter, and download a plain CSV — ideal for database imports or scripts. To get JSON for an API or app, take that CSV through CSV to JSON. Both steps run in the browser with nothing uploaded, and CSV to Excel reverses the process into a formatted workbook.