Frequently Asked Questions

Rocking Tools is a curated studio of single-purpose, high-precision browser utilities for design, security, health, and development. Every tool runs entirely in your browser — nothing is uploaded to any server, and no account is ever required.

Yes. Every tool on Rocking Tools is 100% free to use, with no hidden fees, subscriptions, or paywalls. We are community-supported through optional donations.

No. Zero sign-up. Zero login. Every tool works immediately in your browser without any registration.

Absolutely. All computation happens client-side in your browser using JavaScript. No data — passwords, images, files, measurements, or health information — is ever sent to our servers. Your data never leaves your device.

Once the page has loaded, most tools work fully offline. The computation is local — you just need the initial page load, after which an internet connection is not required for the calculations themselves.

Rocking Tools supports all modern browsers: Chrome, Firefox, Edge, Safari, and Opera on both desktop and mobile. We recommend keeping your browser up-to-date for the best experience.

Use the Contact page to send us a message. We read every message and prioritize bug fixes. Feature requests are tracked and the most-requested ones get built first.

The Screen Ruler measures real-world physical dimensions (millimetres, centimetres, or inches) directly on your screen. It uses your monitor diagonal screen size to calculate the exact pixels-per-inch (PPI) of your display and renders a ruler at true physical scale. No calibration image or physical reference is needed.

The ruler must know your screen physical pixel density (PPI) to convert digital pixels to real-world millimetres or inches. Without the screen size, it cannot determine how many physical millimetres each pixel represents.

Yes. The ruler works on any device with a known screen size. For phones or tablets, simply enter the diagonal screen size in the prompt (e.g. 6.1 inches for an iPhone 13) and the ruler will calibrate accurately.

It calculates matching width and height pairs for any aspect ratio (16:9, 4:5, 1:1, 9:16, etc.) and can also calculate the exact crop box needed to center-crop an image from one ratio to another. It is useful for social media images, video thumbnails, and print layouts.

PPI (Pixels Per Inch) refers to digital screen resolution. DPI (Dots Per Inch) refers to printer resolution. The DPI/PPI Print Size Calculator uses the pixel dimensions of your image and your desired print quality (e.g. 300 DPI) to tell you the maximum physical print size achievable without losing quality.

300 DPI is the standard for professional-quality print such as photos, flyers, and business cards. 150 DPI is acceptable for large-format prints viewed from a distance like banners and posters. 72 to 96 DPI is screen resolution and is not suitable for print.

Your image is never uploaded anywhere. The Image Compressor and Resizer uses the browser built-in Canvas API to compress and resize images entirely in memory on your device. The processed image is then downloaded directly from your browser.

The tool supports JPEG, PNG, WebP, and GIF as input formats. You can export as JPEG or PNG. WebP output is available in browsers that support it such as Chrome, Edge, and Firefox. For best compression ratios, WebP is recommended.

Yes. The Password Strength Checker operates 100% client-side in your browser. Your password is never sent over the network, never logged, and never stored. You can verify this by opening your browser DevTools Network tab — you will see zero requests made when you type.

Strength is calculated using Shannon entropy — a measure of randomness based on the character set size (lowercase, uppercase, numbers, symbols) and password length. A higher entropy means more possible combinations and a longer crack time.

Anything above 60 bits of entropy is considered strong. 80 or more bits is very strong. A 16-character truly random password using mixed case, numbers, and symbols typically achieves 100 or more bits of entropy.

It is an estimate based on modern GPU brute-force attack speeds (approximately 10 billion guesses per second for bcrypt). Real-world times vary based on hashing algorithm, hardware, and attack methodology. Use it as a relative comparison, not an absolute guarantee.

The Calorie Calculator uses the Mifflin-St Jeor equation, the most widely validated formula, to estimate your Basal Metabolic Rate (BMR). It then multiplies by your activity level multiplier to find your Total Daily Energy Expenditure (TDEE) — the number of calories you burn per day.

Macronutrients are protein, carbohydrates, and fat — the three major sources of food energy. The suggested macro split is based on common dietary guidelines: approximately 30 percent protein, 40 percent carbohydrates, and 30 percent fat, adjusted for your goal of deficit, maintenance, or surplus.

The due date is estimated using Naegele Rule, the standard obstetric formula: Last Menstrual Period date plus 280 days (40 weeks). This is the same calculation used by most healthcare providers and is accurate within a 2-week window. It is not a medical diagnosis — always confirm with your OB/GYN.

Ovulation typically occurs 14 days before the next menstrual period. The fertile window is approximately the 5 days before ovulation plus ovulation day itself. Enter your last period date and average cycle length, and the tool calculates these windows for you.

No. All health calculations — calorie needs, pregnancy dates, ovulation windows — run entirely in your browser and are never sent to any server. We collect zero personal health data.

A regular expression is a sequence of characters that forms a search pattern. It is used to match, find, or replace strings in text. Regex is supported in virtually every programming language including JavaScript, Python, Java, PHP, and Go, and is essential for input validation, log parsing, and text transformation.

Enter your regular expression pattern in the Pattern field and your test string in the Test String field. The tool will highlight all matches in real time, show you each capture group value, and indicate any syntax errors in the pattern. You can also use the built-in cheatsheet for quick reference.

The Regex Tester supports the standard JavaScript regex flags: g (global — find all matches), i (case-insensitive), m (multiline — caret and dollar match line boundaries), and s (dotAll — dot matches newlines).

A cron expression is a string of five or six fields separated by spaces that defines a recurring schedule. It is used by Unix/Linux cron jobs, CI/CD pipelines such as GitHub Actions and GitLab CI, cloud schedulers like AWS EventBridge and GCP Cloud Scheduler, and application schedulers like node-cron to trigger tasks automatically.

It provides a visual builder where you set minutes, hours, days, months, and weekdays using dropdowns and inputs — then generates the correct cron string for you. It also parses existing cron strings into human-readable English explanations and shows the next execution timestamps.

Standard Unix cron uses 5 fields: minute, hour, day-of-month, month, and day-of-week. Some schedulers such as Quartz and Spring use 6 fields with an additional seconds field at the start. The Cron Builder supports both formats.

The JSON to CSV to YAML Converter supports bidirectional conversion between all three formats: JSON (JavaScript Object Notation), CSV (Comma-Separated Values), and YAML (YAML Ain't Markup Language). Paste your data in any format and click the target format to convert instantly.

There is no hard limit imposed by the tool — the limit is your browser available memory. The converter handles large datasets such as thousands of rows of CSV or megabytes of JSON efficiently since all processing is done in-memory using JavaScript.

The converter flattens nested JSON objects into CSV columns using dot-notation keys, for example address.city. Deeply nested arrays within rows may be serialised as JSON strings in the corresponding CSV cell. For complex nested structures, YAML is often a better export format as it preserves hierarchy.