Explore Our Tools
Free online tools to make your work easier
Payroll and finance calculators
Visual editor for creating labels with text, barcodes and QR codes. Generate SLP code for label printers easily and intuitively.
Open EditorSpecialized editor for ZPL code (Zebra Programming Language). Create and edit labels for Zebra printers.
Open ZPL EditorEasily convert .env files between different formats. Perfect for developers who work with environment variables.
Open ConverterA fun, interactive game. Perfect for relaxing and having fun during a break from work.
Play NowFind all the pairs in the fewest moves and the shortest time. Three difficulty levels and a best score saved in your browser.
Play NowCheck if a website responds from your browser. Shows “Responded” or “No response” and the time; the result may differ from the real status.
Check WebsiteChecks whether your browser can open a connection to Google and Cloudflare and shows the connection response time. It does not measure internet speed.
Check ConnectionFind your public IP address and copy it in one click. Shows approximate city, region, country and provider when the lookup services respond.
Find My IPGet an image of a page’s top at widths from 320 to 1920 px and download the file. It uses an external service and does not work with logged-in pages.
Capture ScreenshotEstimate your connection’s ping, download and upload speed in the browser, using Cloudflare servers. Approximate, free and nothing to install.
Test SpeedSee whether Google, WhatsApp Web, Steam, Netflix and other services respond from your browser. The result may differ from the real status.
Check ServicesSee the current weather and 3-day forecast for any city: temperature, feels-like, humidity, wind, high and low.
See ForecastTranslate short texts between 9 languages with machine translation. Your text is sent to a third-party service (MyMemory). Free, up to 2,000 characters.
TranslateFree online calculator for basic math: add, subtract, multiply and divide with ease, plus percentage, square root and power.
CalculateBrazil 13th-month salary calculator 2026: 1st installment (due 11/30) and 2nd (due 12/20) with INSS and income tax. Free, no sign-up. Calculate now.
Calculate 13th-Month PayHours worked calculator for Brazil: add clock-in, break and clock-out times, see the weekly total in decimal and your overtime. Free. Calculate now.
Calculate Hours WorkedCompound interest calculator with monthly deposits for Brazil: final amount, chart and year-by-year table in R$. Free, no sign-up. Simulate now.
Calculate Compound InterestSAC and Price financing simulator for Brazil: compare payments and interest, see the amortization table in R$ and download CSV. Free. Simulate now.
Simulate FinancingGenerator and validator for Brazilian CPF and CNPJ (including alphanumeric) for software testing. Valid numbers, with or without mask. Free. Generate now.
Generate CPF/CNPJBrazil contract termination calculator 2026: salary balance, notice period, 13th-month pay, vacation, FGTS fine and withdrawal. Free. Calculate now.
Calculate Termination PaySpain net salary calculator: go from gross to net with Social Security contributions, IRPF withholding and number of payments.
Calculate Net SalarySpain IRPF and tax return calculator: taxable base, net tax and the result of your return, to pay or to be refunded.
Calculate IRPFSpain IVA (VAT) calculator: add or remove 21%, 10% or 4% IVA and get the taxable base, tax amount and total.
Calculate IVASpain mortgage calculator with Euribor: monthly payment, total interest and yearly amortization schedule.
Calculate mortgageConvert US dollar, euro, Brazilian real, pound, yen, yuan and Argentine peso with daily reference rates and the date of the last update.
Convert CurrenciesGenerate random passwords using your browser's cryptographic randomness, 4 to 50 characters, with an entropy meter. Nothing is sent or saved. Free.
Generate PasswordCountdown timer with an end beep and online stopwatch, in hours, minutes and seconds. Works in the browser, free and with no sign-up.
Use TimerMap with OpenStreetMap: search an address, click the map to see the address of a point, mark where you are and open the route in OpenStreetMap.
View MapConvert an image to Base64 and text to upper or lowercase in your browser, with nothing sent to a server. It does not convert PDF or Word.
Convert FilePreview labels in Direct Protocol with JSON data. Supports PP, FT, PT, BARSET (QR Code and Code 39) and PB. Visual approximation, no data sent.
Simulate LabelWhy use DarkBoxKit?
DarkBoxKit is a collection of free online tools built to make everyday tasks easier for developers, designers and professionals. All of the tools are:
- ✅ Completely free - No hidden costs
- ✅ Online - Nothing to install
- ✅ Intuitive - Easy-to-use interface
- ✅ Private - Most tools run in your own browser (see the Privacy Policy)
- ✅ Up to date - Always getting improvements
Work and money calculations
For everyday work and money matters, there is the 2026 13th salary calculator (1st and 2nd installment, with social security and income tax), the employment termination pay calculator, the work hours calculator, the SAC and Price loan simulator and the compound interest calculator. The calculations run in the browser, and each page explains the formula and includes examples (tools designed for Brazilian legislation, amounts in reais).
Tools for developers and labels
For anyone who develops software or prints labels, there is the SLP Label Editor, the ZPL Editor, the Env Converter, the CPF and CNPJ generator and validator for software testing and the password generator.
Internet, utilities and fun
For everything else, there is the currency converter, the speed test, the weather forecast, the map with navigation, the timer and stopwatch, the Secret Santa organizer Secret Friends and the memory game.