LittleKit help centre
Understand the tool before you use it.
Browse how each operation handles input, what the result means and where its limits are. The detailed guides are reviewed alongside the tools they describe.
122 tool references32 detailed tool guides6 practical articles
122 tool references, grouped by category. Searches stay in this tab.
Image tools
Browse category Image tools
Batch Image StudioResize, compress and convert an image collection in one local pass.Image CompressorRe-encodes raster pixels with a selected JPEG or WebP quality level.Image ResizerResamples pixels to a target width and height.Image CropperCopies the rectangle starting at X,Y with your chosen width and height into a new image.JPG → PNGDecodes JPG pixels and re-encodes them as PNG in your browser.PNG → JPGDecodes PNG pixels and re-encodes them as JPG in your browser.JPG → WEBPDecodes JPG pixels and re-encodes them as WEBP in your browser.PNG → WEBPDecodes PNG pixels and re-encodes them as WEBP in your browser.WEBP → PNGDecodes WEBP pixels and re-encodes them as PNG in your browser.WEBP → JPGDecodes WEBP pixels and re-encodes them as JPG in your browser.Image Dimensions InspectorReads decoded pixel width and height, MIME format, byte size and aspect ratio.Image Metadata ViewerParses available EXIF and other supported image tags locally, including camera and location fields when present.Image Metadata RemoverCreates a fresh PNG from decoded pixels, discarding original EXIF, GPS, comments and other source metadata.Image RotatorRotates decoded pixels clockwise by 90, 180 or 270 degrees.Image FlipperMirrors pixels horizontally or vertically.Aspect Ratio CalculatorFind the simplest width-to-height ratio.
PDF tools
Browse category PDF tools
Compress PDFRebuilds every page from a compressed JPEG at a chosen resolution to reduce image-heavy and scanned PDFs.PDF to ImagesRenders each PDF page to a downloadable JPG or PNG image in the browser.PDF to TextExtracts selectable text from chosen PDF pages locally and formats it with page separators for copying or download.Merge PDFCopies pages from each selected PDF into one new document, in the visible file order.Split PDFCreates one separate downloadable PDF for every page of the source.Extract PDF PagesCopies selected page numbers or ranges into a new PDF in the specified order.Remove PDF PagesCopies all pages except the selected page numbers into a new PDF.Rotate PDFAdds the selected clockwise rotation to each page’s existing rotation.Reorder PDF PagesPreview pages, insert A4 or US Letter blank pages or pages from other PDFs at a chosen position, reorder, duplicate, rotate, remove or extract, then export one local copy.Watermark PDFAdds translucent diagonal text to every page of a new PDF copy.Add Page Numbers to PDFAdds a customizable footer to every page, with current-page and total-page placeholders.Crop PDF PagesChanges the visible crop box of every page using top, right, bottom and left margins in points.Insert Blank PDF PagesInserts up to 20 blank pages before a chosen page or at the end, matching the neighboring page size.PDF Metadata ViewerReads standard document information fields, page count and whether a document-level XMP stream exists.PDF Metadata RemoverRemoves the document Info dictionary and document-level XMP metadata stream.Flattened PDF RedactionMarks sensitive visible areas, paints them opaque black, then rebuilds every page as a new raster image in a fresh PDF so source text and hidden PDF objects are not copied.PDF Pack BuilderCombines selected PDFs, optionally rearranges or duplicates pages, then adds document title, author, a text watermark and page-number footer in one local workflow.PDF Metadata EditorUpdates the standard title, author, subject, keywords, creator and producer fields in a new copy of the PDF.Visual PDF EditorRenders each PDF page and lets you click to place text or drag highlights, lines and whiteout covers directly on the document.PDF Form FillerDetects named AcroForm text boxes, checkboxes, dropdowns, radio groups and option lists, then fills them in a new PDF copy.Images to PDFPlaces a sequence of JPG, PNG or WebP images into a new PDF, with reorder controls, fit-to-image pages or A4 pages and margins.Visual PDF ComparisonRenders matching page numbers from two PDFs locally and highlights visible pixel differences above a configurable tolerance.
Text tools
Browse category Text tools
Word CounterCounts Unicode letter/number sequences, keeping internal apostrophes and hyphens together.Character CounterCounts user-perceived grapheme clusters rather than UTF-16 code units.Case ConverterChanges the capitalization of your text using the selected rule.Title Case ConverterCapitalizes English words while keeping short connecting words lowercase inside a title.Remove Duplicate LinesKeeps the first occurrence of each exact, case-sensitive line.Sort LinesSorts complete lines with English collation; numeric mode compares embedded numbers naturally.Reverse TextReverses grapheme clusters so emoji and combining characters stay intact.Reverse LinesReverses line order without reversing words inside each line.Remove Extra SpacesTrims each line and collapses horizontal whitespace; keeps line breaks.Find And ReplaceReplaces every case-sensitive literal match.Text DifferenceUses a longest-common-subsequence line comparison.Slug GeneratorNormalizes accents, lowercases text and joins letter/number groups with hyphens.Random String GeneratorUses Web Crypto randomness with rejection sampling to avoid modulo bias.Lorem Ipsum GeneratorRepeats neutral Latin-style placeholder paragraphs for layout testing.Duplicate Word FinderCounts case-insensitive words and reports those used more than once.Reading Time CalculatorReading minutes = word count ÷ words per minute.Text StatisticsCombines Unicode word, grapheme, line and English sentence counts.Line CounterCounts newline-separated lines, including blank and trailing lines.Sentence CounterUses the browser’s English sentence segmenter, excluding empty segments.
Developer tools
Browse category Developer tools
JSON to CSVBuilds CSV columns from the union of object keys, preserving first-seen order.JSON FlattenerConverts nested JSON leaves into JSON Pointer paths.JSON to JSON LinesSerializes each element of a JSON array as one independent compact JSON line.JSON Lines to JSONParses each nonblank line separately and collects the records into one JSON array.JSON FormatterParses strict JSON and serializes with two-space indentation.JSON ValidatorUses the browser’s strict JSON parser.JSON MinifierParses strict JSON and removes insignificant formatting whitespace.Base64 EncodeEncodes text as UTF-8 bytes, then standard Base64.Base64 DecodeDecodes standard Base64 bytes as strict UTF-8 text.URL EncodePercent-encodes one URL component using UTF-8.URL DecodeDecodes percent-encoded UTF-8 sequences in a URL component.HTML EncodeEscapes &, <, >, double quotes and apostrophes for HTML text.HTML DecodeDecodes numeric entities and amp, lt, gt, quot, apos and nbsp.UUID GeneratorGenerates random version-4 UUIDs with the browser’s Web Crypto API.Unix Timestamp ConverterUnix time measures elapsed seconds or milliseconds since 1970-01-01T00:00:00Z.Regex TesterRuns JavaScript regular expressions in an isolated Web Worker with a 300 ms execution limit.JWT DecoderBase64url-decodes the header and payload as UTF-8 JSON.
Unit converters
Browse category Unit converters
Length ConverterConvert length in both directions with clearly named units.Weight / Mass ConverterConvert mass in both directions with clearly named units.Temperature ConverterConvert temperature in both directions with clearly named units.Area ConverterConvert area in both directions with clearly named units.Volume ConverterConvert volume in both directions with clearly named units.Speed ConverterConvert speed in both directions with clearly named units.Pressure ConverterConvert pressure in both directions with clearly named units.Energy ConverterConvert energy in both directions with clearly named units.Power ConverterConvert power in both directions with clearly named units.Digital Storage ConverterConvert digital storage in both directions with clearly named units.Data Transfer Rate ConverterConvert data transfer rate in both directions with clearly named units.Time ConverterConvert time in both directions with clearly named units.Angle ConverterConvert angle in both directions with clearly named units.Fuel Economy ConverterConvert fuel economy in both directions with clearly named units.
Time & date
Browse category Time & date
Age CalculatorCounts completed calendar years, then separately calculates elapsed calendar days.Date DifferenceElapsed days = (end UTC midnight − start UTC midnight) ÷ 86,400,000.Add / Subtract DaysAdds a signed whole number of calendar days, rolling across month and year boundaries.Business Days CalculatorCounts Monday–Friday after the start date through the end date, subtracting unique supplied weekday holidays.Week NumberISO 8601 weeks start Monday.Day Of YearJanuary 1 is day 1.Leap Year CheckerA year is leap if divisible by 4, except centuries unless divisible by 400.Countdown CreatorSubtracts the current clock time from a target interpreted in the device’s timezone, updating each second.Duration CalculatorTotal seconds = hours × 3600 + minutes × 60 + seconds.Time Duration CalculatorSubtracts start clock minutes from end clock minutes; optionally wraps an earlier end into the next day.
Calculators
Browse category Calculators
Mortgage Repayment CalculatorMonthly payment = P × r ÷ (1 − (1 + r)^−n), where P is principal, r is nominal annual rate ÷ 12, and n is term in months.Percentage CalculatorResult = percentage ÷ 100 × number.Percentage ChangeChange = (new − original) ÷ |original| × 100.Percentage DifferenceDifference = |a − b| ÷ ((a + b) / 2) × 100.Ratio CalculatorDivides both integer terms by their greatest common divisor.Fraction CalculatorUses common denominators for addition/subtraction and cross products for multiplication/division, then reduces by GCD.Average CalculatorArithmetic mean = sum of values ÷ count.Median CalculatorSorts values; returns the middle value or mean of the two middle values.Standard Deviation CalculatorWelford’s algorithm accumulates squared deviations.GCD CalculatorEuclid’s remainder algorithm finds the greatest common divisor.LCM CalculatorLCM(a,b) = |a ÷ GCD(a,b) × b|, folded across the list.Prime Number CheckerTests divisibility by 2 and odd integers through the square root.Scientific CalculatorA bounded recursive-descent parser supports + − * / % ^, parentheses, pi, e, sin/cos/tan, inverse trig, sqrt, abs, ln, log, exp, floor and ceil.Random Number GeneratorWeb Crypto rejection sampling gives each integer in the inclusive range equal probability.Decimal ↔ FractionFinite decimals become an integer over a power of ten, then reduce by GCD.Roman Numeral ConverterUses standard subtractive Roman notation: IV, IX, XL, XC, CD and CM.
Colour & design
Browse category Colour & design
HEX ↔ RGBHEX encodes three 8-bit sRGB channels in base 16; RGB shows them as decimal values.HEX ↔ HSLConverts between 8-bit sRGB and hue, saturation, lightness using channel extrema.RGB ↔ HSLHSL derives hue from the dominant RGB channel and lightness from the average channel extrema.Colour PickerThe native colour picker supplies an sRGB colour; the tool displays HEX, RGB and HSL equivalents.Contrast CheckerWCAG 2.x: linearize sRGB at 0.04045, L = 0.2126R + 0.7152G + 0.0722B.Gradient GeneratorCreates a CSS linear-gradient between two colours at the supplied angle.CSS Box Shadow GeneratorCSS box-shadow uses horizontal offset, vertical offset, blur radius, spread radius and colour.Border Radius GeneratorCSS corner order is top-left, top-right, bottom-right, bottom-left.
Learn by task
All guides Practical guides
How to make a PDF smaller without losing the text layerA practical way to diagnose a large PDF, choose the least destructive compression approach and verify the downloaded result.Redacting a PDF: cover-up, flattening and what to verifyUnderstand the difference between a visual cover and a flattened PDF copy before sharing sensitive information.A reliable checklist for preparing a PDF to shareA short local workflow for putting pages in order, checking metadata, reducing size and verifying a PDF before sending it.JPG, PNG or WebP: choosing an image format for the jobA practical guide to choosing a still-image format based on photography, transparency, detail and compatibility.Remove image metadata before sharing a photographLearn what EXIF metadata can reveal, what stripping it does not change and how to verify the exported image.Format JSON locally without leaking secretsA safe, practical workflow for making JSON readable while keeping tokens, keys and personal data out of hosted formatters.