S3eidat Tools

Monthly payment, total interest, total paid and payoff month for a fixed-rate loan or mortgage, with an optional extra monthly payment (shows interest saved and how much sooner it ends) and an amortization schedule by year or by month (or none). Maths is in whole cents like the website; the last payment absorbs the rounding so the balance ends at 0. Rate 0–100 %, term 1 month to 100 years. Web version: https://s3eidat.github.io/loan-calc/

Every percentage question the website answers: "X% of Y" (percent_of: percent, value), "X is what % of Y" (what_percent: part, whole), percent change from A to B (change: from, to), increase/decrease a value by X% (increase/decrease: value, percent), find the original before a X% increase/decrease (reverse_increase/reverse_decrease: value, percent), and profit margin vs markup (margin_markup: cost, price). Returns the number, a display string and the worked formula. Web version: https://s3eidat.github.io/percentage-calc/

Number theory with big integers, like the website. check: is a number prime (trial division, deterministic Miller-Rabin below 2^64, probabilistic above), its prime factorisation (Pollard rho), number of divisors, sum of divisors σ, Euler φ, the divisor list, previous/next prime and whether it is perfect; the number may be an expression like "2^61-1", "10!+1" or "1000003*1000033" (up to 400 digits). gcd_lcm: GCD and LCM of 2–50 numbers with Euclid's steps. range: list the primes between two numbers (below 10^15, at most 10,000,000 numbers per range). Web version: https://s3eidat.github.io/prime-tools/

Convert numbers to Roman numerals (1–3,999 in standard form; up to 3,999,999 with a vinculum bar, which multiplies by 1,000) and Roman numerals back to numbers with strict validation that explains mistakes (IIII, IC, VV, non-standard forms like IIX…) and the symbol-by-symbol working. Also writes a date in Roman numerals (day/month/year order and separator of your choice, years 1–3999). Web version: https://s3eidat.github.io/roman-numerals/

Convert pay between per hour, day, week, every 2 weeks, twice a month, month and year using your hours per week, days per week and weeks per year (defaults 40 / 5 / 52). Optional overtime (hours per week × multiplier, e.g. 1.25, 1.5, 2) and a raise given as a percent or as the new monthly pay. Amounts are rounded to 2 decimals. Web version: https://s3eidat.github.io/salary-calc/

Sleep in whole cycles so you wake in light sleep: given a wake-up time, the bedtimes for 6, 5, 4 or 3 cycles; given a bedtime (or "now"), the wake-up times. Defaults: 90-minute cycles (70–110) and 15 minutes to fall asleep (0–60). With mode "bed"/"now" it also lists nap alarms (20, 30, 60 min and one full cycle). 12- or 24-hour clock. Web version: https://s3eidat.github.io/sleep-calc/

Split a restaurant bill with tax/service and tip, in whole cents so the shares always add up exactly (left-over cents go to the largest remainders). simple: one bill split evenly between N people (1–100). items: list who had what; each item is split between the people who shared it (nobody listed = everyone), and tax and tip are shared in proportion. Tip can be on the subtotal or on subtotal + tax; each share can be rounded up to a step (e.g. 0.5 or 1). Returns a ready-to-send summary. Web version: https://s3eidat.github.io/split-bill/

Descriptive statistics for a list of numbers: count, sum, mean, median, mode(s), min, max, range, sample and population variance and SD, standard error, coefficient of variation, quartiles (inclusive = Excel QUARTILE.INC, exclusive = QUARTILE.EXC, or Tukey median-of-halves), IQR, 1.5×IQR outlier fences and outliers, a frequency table (values, or Sturges bins when there are more than 20 distinct values) and z-scores. Paste numbers separated by spaces, commas, semicolons, | or new lines; headers and text are skipped and reported. Commas can be separators, thousands marks or decimal commas. Up to 1,000,000 numbers. Web version: https://s3eidat.github.io/stats-calc/

Convert between units in 14 categories, the same table as the website: length, mass, temperature, volume, area (incl. dunam), speed, time, data (kB/MB vs KiB/MiB, bits), pressure, energy, power, angle, fuel economy (L/100km, km/L, mpg US/UK) and cooking (tsp, tbsp, cups, metric spoons). Give value + from + to (symbols like "km", "°F", "GiB" or names like "miles"; ASCII forms like "m2", "um" work), or a query like "5 km to mi". Set all=true for the value in every unit of the category, or list=true to see every category and unit. Web version: https://s3eidat.github.io/unit-convert/

Zakat on wealth: 2.5 % of net zakatable wealth (cash, bank, investments, trade goods, money owed to you, gold and silver, minus debts due now) when it reaches the nisab: the value of 85 g of pure gold (default) or 595 g of silver. Gold weight is converted to pure gold by karat (24/22/21/18). You give today's gold/silver price per gram in your currency: nothing is fetched from the network. An estimate only; consult a scholar. Web version: https://s3eidat.github.io/zakat-calc/

Convert Unix file permissions between octal (755, 0644, 4755), symbolic (rwxr-xr-x, ls -l style -rwsr-xr-x) and chmod clauses (u=rwx,g=rx,o=; relative ones like g+w or +x apply to "base"). Returns all forms, a plain-English description per owner/group/others, setuid/setgid/sticky meaning, safety warnings, and ready chmod commands. Web version: https://s3eidat.github.io/chmod-calc/

Explain a standard 5-field cron expression (minute hour day-of-month month day-of-week; names like MON/JAN, ranges, lists, steps, ? and the @hourly/@daily/@weekly/@monthly/@yearly/@reboot macros) in plain English and list the next run times in an IANA timezone. Follows Vixie cron: when both day fields are restricted a day matches either one. Quartz 6/7-field and L/W/# syntax are rejected with a clear message; per-field errors are reported. Web version: https://s3eidat.github.io/cron-explain/

Decrypt an .s3enc file made by the S3eidat File Encrypt website or crypto_file_encrypt, verify every chunk, and write the original file back under its stored (sanitised) name. A wrong password, damage, truncation or reordering is reported and nothing is written. Web version: https://s3eidat.github.io/file-encrypt/

Encrypt any file with a password into the website's .s3enc format: chunked AES-256-GCM, key from PBKDF2-SHA256 (600,000 rounds, random salt), original name/type/size stored encrypted inside, tamper/truncation/reorder-proof. Files made here open at https://s3eidat.github.io/file-encrypt/ and vice versa (crypto_file_decrypt). Whole file is processed in memory (size limit = server --max-mb). Web version: https://s3eidat.github.io/file-encrypt/

Hide a text message inside an image (LSB steganography in R, G, B; the picture looks the same) and save it as a lossless PNG, optionally encrypted with a password (AES-256-GCM, PBKDF2-SHA256 600,000). Same bit layout as the website, so the PNG reveals at https://s3eidat.github.io/stego-image/ or with crypto_stego_reveal. Capacity ≈ width×height×3/8 − 10 bytes (−44 more when encrypted). Transparency is filled with white. The result is read back and checked before returning. Sending it through apps that recompress images (JPEG, chat apps) destroys the message. Web version: https://s3eidat.github.io/stego-image/

Read a message hidden in a PNG by the S3eidat Stego Image website or crypto_stego_hide (decrypting it if a password was used). Reports when there is no message, e.g. because the image was recompressed (JPEG), resized or edited. Web version: https://s3eidat.github.io/stego-image/

Decrypt an "S3E1.…" message made by the S3eidat Text Encrypt website or crypto_text_encrypt, with its password. Verifies integrity: a wrong password or any change to the text is reported, never garbage output. Accepts base64url and line breaks. Web version: https://s3eidat.github.io/text-encrypt/

Encrypt a message with a password: AES-256-GCM, key from PBKDF2-SHA256 (600,000 rounds, random 16-byte salt, 12-byte IV), output as one "S3E1.…" base64 line. Exactly the website's format, so the result can be decrypted at https://s3eidat.github.io/text-encrypt/ or with crypto_text_decrypt. Each run gives a different output. Web version: https://s3eidat.github.io/text-encrypt/

Build a fluid typography/spacing value: CSS clamp() that grows linearly from a size at a small viewport to a size at a large viewport (sizes and viewports in px), expressed in rem or px. Also returns the computed size at sample viewport widths. Web version: https://s3eidat.github.io/css-units/

Beautify CSS (one declaration per line, one selector per line, blank line between top-level rules, nested @media blocks) or minify it. Strings, url(...) and escapes are kept intact; calc() spacing is preserved. Optional comment removal (/*! … */ kept). Give "text" or a file "path". Web version: https://s3eidat.github.io/html-css-format/

Convert a CSS length between px, rem, em, %, pt, pc, in, cm, mm, vw, vh, vmin and vmax, using a root font size, parent font size and viewport size (defaults 16px / 16px / 1440×900). Uses the CSS definition of 96px per inch. Returns every unit, rounded to 4 decimals by default. Web version: https://s3eidat.github.io/css-units/

Convert CSV/TSV to JSON with an RFC 4180 parser (quoted fields, "" escapes, line breaks inside quotes, CR/LF/CRLF, BOM). Detects the delimiter (comma, semicolon, tab, pipe), uses the first row as headers (blank → column_N, duplicates → name_2), and can type values (numbers, true/false, null; long digit strings like IDs stay strings). Output: array of objects or array of arrays, pretty-printed. Give "text" or a file "path". Web version: https://s3eidat.github.io/csv-json/

Convert a curl command (bash/zsh quoting incl. $'…', line continuations, "Copy as cURL" from browsers) into code for JavaScript fetch, axios, Python requests, PHP cURL, Go net/http or Node.js http/https: every target the website supports. Understands -X, -H, -d/--data-raw/--data-binary/--data-urlencode, --json, -F forms and files, -u, -b, -A, -e, -G, -I, -k, -L, -m, --connect-timeout, -x, -T, --compressed, --oauth2-bearer. Also returns the parsed request (secrets masked unless revealSecrets) and notes on what could not be converted. Only parses text; never sends the request. Web version: https://s3eidat.github.io/curl-convert/

Make a printable attendance / sign-in sheet PDF: names down the side, one column per date for a month (skipping chosen weekdays, e.g. Fri+Sat or Sat+Sun), a run of N sessions from a start date, or N blank columns; tick boxes or wide signature cells; row numbers, a total column, extra empty rows, title, group and teacher. Same page maths as the website: rows that don't fit continue on more pages, and too many date columns are split across pages with the same names. Also returns a blank register CSV. English labels, Latin text only for now. Web version: https://s3eidat.github.io/attendance-sheet/

Design business cards and get a print-ready PDF sheet: cards centred on A4 or Letter with crop marks (10 per sheet for 85 × 55 mm EU or 3.5 × 2 in US cards), plus a back side page mirrored for long-edge duplex printing. Four front templates (classic, band, centered, minimal), backs with your logo, a "scan to save my contact" vCard QR code, or blank; six colour themes or your own accent/paper/ink colours; optional logo and a vCard QR on the front. Also returns the vCard text. Print at 100% / actual size. Latin text only for now (the website also does an Arabic side). Web version: https://s3eidat.github.io/business-card/

Make a printable calendar PDF: a month grid (one page per month, several months in a row if you like) or a whole year on one page, A4 or Letter, landscape or portrait. Week starts on Saturday (default, like the website), Sunday or Monday; optional Hijri (Umm al-Qura) dates; events (one-off or yearly, 7 colours) shown in the day cells, or as coloured days plus a legend in the year view; optional title. English names by default; other Latin-script locales (fr, de, es, tr…) use their own month/day names. Web version: https://s3eidat.github.io/calendar-maker/

Make a clean A4 invoice PDF: your business (logo, name, address, email, phone, tax ID), client, invoice number and dates, line items with quantity, unit price, per-line discount % and tax %, subtotal, discount, tax per rate and total, notes, payment terms, and an optional PAID stamp. Same maths as the website: every line is rounded to the currency's minor unit (2 decimals, 3 for JOD/KWD/BHD/OMR/TND…, 0 for JPY…) with half-up rounding; amounts formatted en-US style ($1,234.50, JOD 10.124). Long item lists continue on more pages. Returns the PDF path and the computed totals. Latin text only for now. Web version: https://s3eidat.github.io/invoice-maker/

Print address or product labels on standard sticker sheets as PDF: A4 21/24/14/40/65-up (L7160, L7159, L7163, L7654, L7651 sizes) or Letter 30/10/80-up (5160, 5163, 5167 sizes), or custom geometry in mm. Text modes: "list" (one label per block, blank line between labels), "csv" (rows filled into a template like "{Name}\n{Street}\n{City} {Postcode}", header row or {1},{2}…), or "same" (one text × count). Copies per label, start at a later position to reuse a part-used sheet, alignment, font, size, bold first line, border, shrink-to-fit and printer offset nudges. Print at 100% / actual size. Up to 3000 labels. Latin text only for now. Web version: https://s3eidat.github.io/label-maker/

Make a simple sales receipt as PDF: an 80 mm thermal-roll receipt (page height fits the content, monospace) or an A5 page. Shop header (name, address, phone, tax number), receipt number with prefix, date/time, customer, items (name × qty × price), discount (% or fixed amount), tax % after discount, total, payment method, amount paid and change, note and footer. Same maths as the website: amounts rounded half-up to 0, 2 or 3 decimals. Also returns the totals and a 32-column plain-text version. English labels, Latin text only for now. Web version: https://s3eidat.github.io/receipt-maker/

Turn structured CV fields into a clean A4 resume PDF: contact header, summary, experience, education, skills, projects and languages, in any section order, with three templates like the website: "classic" (centred header and accent rule), "modern" (coloured sidebar with contact, skills and languages) and "compact" (denser, headings in a left column). Description lines starting with "-", "•", "*" or "–" become bullet points; skills are comma-separated. Aims for one page; longer CVs continue on a second page. English headings, Latin text only for now. Web version: https://s3eidat.github.io/resume-builder/

Build a .gitignore by combining the website's templates for languages, frameworks, mobile, game engines, tools, OSes and editors (node, python, java, android, ios, flutter, reactnative, unity, unreal, go, rust, cpp, dotnet, php, wordpress, rails, django, nextjs, vite, docker, terraform, macos, windows, linux, vscode, jetbrains, vim). Templates can be named by id, name or keyword (e.g. "javascript" → node). Duplicate patterns are removed, optional "### Name ###" section headers, plus your own custom lines at the end. Returns the text, or writes it to "output" (e.g. "./.gitignore"). Set "list" to see all templates. Web version: https://s3eidat.github.io/gitignore-gen/

Compute MD5, SHA-1, SHA-256 and SHA-512 of text or a file (path or base64), optionally an HMAC with a key, and check against an expected checksum (hex in any case/spacing, "SHA256 (file) = …" lines, or base64). Web version: https://s3eidat.github.io/hash-lab/

Beautify (indent block elements, keep inline runs on one line) or minify HTML with a forgiving tokenizer: implied end tags (<p>, <li>, <td>…), void elements, and <script>, <style>, <pre>, <textarea> contents kept byte-for-byte. Whitespace between attributes is normalised; attribute values are never changed. Optional comment removal (IE conditional comments kept). Text only: nothing is rendered or run. Give "text" or a file "path". Web version: https://s3eidat.github.io/html-css-format/

Look up HTTP status codes: by exact code (e.g. 418, also non-standard ones like 499 or 524), by code prefix ("50"), or by words ("too many", "redirect post"), optionally limited to a class (1xx–5xx). Each result has the name, what it means, when to use it, common causes and the defining spec. Non-standard nginx/Cloudflare codes are only searched when "includeNonStandard" is set. Web version: https://s3eidat.github.io/http-status/

Generate 1–1000 unique IDs with a cryptographic RNG: UUID v4 (random), UUID v7 (time-ordered, RFC 9562, strictly increasing within a batch), ULID (26 Crockford Base32 chars, monotonic) or NanoID (custom length 2–128 and alphabet: URL-safe default, alphanumeric, hex, digits, no look-alikes, or your own). Options: uppercase, no dashes. Web version: https://s3eidat.github.io/uuid-forge/

Check whether a string is a valid UUID (any version; braces, urn:uuid: and missing dashes accepted) or ULID, and report its version, variant and canonical form. For UUID v1, v6, v7 and ULID also returns the embedded creation time. Web version: https://s3eidat.github.io/uuid-forge/

Turn an image into ASCII art: each character cell takes the average brightness of its area (cells are twice as tall as wide) and maps it onto a character ramp: standard " .:-=+*#%@", detailed (70 characters), blocks " ░▒▓█", simple, binary, or your own. Contrast, brightness and invert (for light text on dark backgrounds). Returns the text; format "png" also renders it to an image (optionally in the image's colours). Transparent areas count as white paper. Web version: https://s3eidat.github.io/ascii-art/

Big banner letters from text, using the website's own bitmap fonts: block (█ 5×7), char (any fill character, e.g. #), shadow (█ with ░ shade), compact (half-block 5×7), small (█ 3×5), tiny (half-block 3×5). Letters A-Z, digits and common punctuation (unknown characters show as "?"); one banner per input line. Returns the text; format "png" also renders it to banner.png. Web version: https://s3eidat.github.io/ascii-art/

Make an image file smaller: re-encode at a quality (default 80) and optionally cap the longest side (maxSide), as JPEG, WebP, AVIF or PNG ("keep" = same format; GIF/BMP/TIFF become PNG). Or give targetBytes to find the highest quality that fits that size. With keepSmaller (default on) the original is kept when re-encoding would not make it smaller. Reports before/after sizes and % saved. Transparent areas become white in JPEG. Metadata (EXIF, GPS) is not copied. PNG is lossless (quality ignored). Web version: https://s3eidat.github.io/image-squeeze/

Convert an image to PNG, JPEG, WebP, AVIF, GIF or TIFF. Reads JPEG, PNG, WebP, AVIF/HEIF, GIF (first frame), TIFF, SVG, BMP and ICO. Transparent areas are filled with `background` when writing JPEG (or always with `flatten`). EXIF rotation is applied. SVGs are rasterised at their own size (width/height or viewBox; 1024×1024 if neither), scripts never run. Images larger than 16384 px a side or 100 MP are scaled down to fit. Web version: https://s3eidat.github.io/image-convert/

Crop an image to a pixel box (x, y, width, height) or to an aspect ratio (1:1, 4:5, 3:2, 16:9, 9:16, "W:H" or a number), taking the largest centred region (or aligned to an edge with `position`). Boxes are kept inside the image. Output JPEG/PNG/WebP/AVIF, name <name>-<W>x<H>.<ext>. Web version: https://s3eidat.github.io/image-resize/

Show the hidden metadata in a photo: camera make/model, lens, date taken, exposure, ISO, software, author/copyright, serial numbers, comments, PNG text chunks, and GPS coordinates (where the photo was taken). Lists every metadata block (EXIF, XMP, ICC, IPTC, embedded previews) with its size and flags privacy-sensitive fields. JPEG and PNG fully; WebP/AVIF/HEIC/TIFF EXIF via sharp. Web version: https://s3eidat.github.io/exif-cleaner/

Remove EXIF, GPS location, XMP, IPTC, comments, PNG text chunks and embedded previews from a photo before sharing it. JPEG and PNG are cleaned losslessly (image data copied byte for byte, like the website); by default the rotation is kept as a tiny orientation-only EXIF and the ICC colour profile is kept. applyOrientation re-encodes JPEGs with the rotation baked into the pixels. WebP/AVIF/HEIC/TIFF are re-encoded without metadata. Output name <name>-clean.<ext>. Web version: https://s3eidat.github.io/exif-cleaner/