Immediate access
Open a tool, paste content or select files, then copy the result.
39 free online tools
Free tools for developers, makers and QA workflows.
Convert, compress, validate, generate and calculate from one fast catalog. OnSubmit groups practical browser-based tools for PDFs, images, text, developer data, test data and everyday calculations.
6 categories Local processing Fast to use
Tools
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39 result(s)
UUID Generator Generate UUID v4 identifiers for databases, APIs, fixtures and distributed systems. Open tool Password Generator Create strong random passwords with configurable length, letters, numbers and symbols. Open tool URL Encoder / Decoder Encode or decode URLs, query strings and percent-encoded text. Open tool JSON Formatter Format, indent and validate JSON, XML or SQL snippets for debugging and documentation. Open tool Regex Tester Test JavaScript regular expressions, flags, matches and replacements. Open tool JWT Decoder / Encoder Decode, inspect and regenerate test JSON Web Tokens with HS256. Open tool Cron Expression Parser Parse a cron expression and preview upcoming run times. Open tool MD5 Hash Generator Calculate and compare the MD5 digest of UTF-8 text or local files for checksums, compatibility and legacy workflows. Open tool Timestamp Converter Convert Unix timestamps to readable dates and dates back to Unix time. Open tool Base64 Encoder / Decoder Encode text to Base64 and decode Base64 back to readable text. Open tool Markdown to HTML Convert Markdown to readable HTML with a live preview. Open tool Lorem Ipsum Generator Generate placeholder text for wireframes, prototypes, templates and layout tests. Open tool Diff Checker Compare two texts, JSON snippets or code blocks by line, word or character and highlight aligned additions and removals. Open tool QR Code Generator Create a QR code PNG for a URL, text, contact detail or shareable information. Open tool HEIC to JPG Convert HEIC or HEIF photos to JPG for wider compatibility. Open tool Image Compressor Reduce JPG or PNG file size and adjust image width before publishing or sharing. Open tool Merge PDF Merge multiple PDF files into a single document. Open tool Image to PDF Convert one or more JPG or PNG images into a PDF document. Open tool Word Counter Count words, characters, sentences, reading time and term density in a text. Open tool Timezone Converter Compare a date and time across Paris, London, New York, San Francisco, Tokyo, Sydney and UTC. Open tool Color Converter Convert colors between HEX, RGB and HSL with a visual preview. Open tool Loan Calculator Estimate loan payments, insurance, interest and financing cost from project amount, down payment, rate and duration. Open tool French Notary Fees Calculator Estimate notary fees for a property purchase in France, old or new. Open tool VAT Calculator Convert net price to gross price, calculate VAT or recover net price from gross. Open tool Gross Net Salary Calculator Estimate net salary from gross salary, and gross from net, for French salary scenarios. Open tool IBAN & BIC Validator Validate IBAN and BIC format, country length and checksum structure. Open tool IBAN & BIC Generator Generate fictitious IBAN and BIC values by country for banking forms, QA, mockups and fixtures. Open tool Test Credit Card Generator Generate fictitious credit card numbers for form tests using Luhn-compatible values. Open tool French SIRET / SIREN Generator Generate fictitious French SIREN and SIRET numbers with valid control keys for tests. Open tool SIRET / SIREN Validator Validate the length, structure and Luhn key of French SIREN or SIRET numbers. Open tool French VAT Generator & Validator Generate a French VAT number from a valid SIREN or SIRET, then check its local format and key. Open tool Fake French Address Generator Generate synthetic French test addresses with coherent city and postal-code pairs for forms, CRM, checkout and QA datasets. Open tool Fake Identity Generator Generate fictitious user profiles for form tests, prototypes, QA and mockups. Open tool Fake French Company Generator Generate coherent synthetic French company data with SIREN, SIRET, VAT, address, contact, IBAN/BIC and UUID. Open tool CSV JSON Converter Convert CSV to JSON and JSON back to CSV directly in the browser. Open tool JSON to TypeScript Generate TypeScript interfaces from a representative JSON example. Open tool YAML JSON Converter Convert YAML to JSON and JSON back to YAML for configuration and API workflows. Open tool SHA256 / SHA512 Generator Calculate SHA-256, SHA-384 and SHA-512 hashes for text. Open tool .env Example Generator Turn a .env file into a safe .env.example without exposing secrets. Open tool
Workflows
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Useful workflows that connect several tools around the same task.
8 tools Test data Generate identifiers, fake profiles, addresses, banking details and company data to test interfaces without using real personal data. 6 tools Banking test data Prepare fictitious banking values to test SEPA forms, IBAN/BIC fields, French RIB details, payment methods and billing workflows. 7 tools Business invoicing Group the tools needed to prepare invoice tests, check French company identifiers, calculate VAT and validate French VAT number structure. 6 tools Finance calculators Estimate loan payments, VAT, gross/net amounts, salary and French notary fees for invoices, purchases and budget scenarios. 7 tools Data converters Convert, format and compare structured data for APIs, exports, configuration files, documentation and developer integrations. 6 tools Security and hash Generate passwords, calculate SHA hashes, inspect JWTs and prepare .env.example files without exposing production secrets.
Why OnSubmit
Simple tools that open fast and stay useful
Browser-first
Compatible tasks run directly on your device to keep short workflows short.
Explicit limits
Each tool states whether the result is generated, locally validated, converted or calculated, and when an official source is still required.
FAQ
Frequently asked questions
Are files sent to a server?
Compatible tools process data directly in the browser. If a tool requires external processing, the page should make that clear before use.
What is the difference between generating and validating data?
A generator creates synthetic test data. A validator checks format or checksum rules without proving that the value exists in the real world.
Do I need an account?
No. Public OnSubmit tools are free to use without signup.