Percentage Calculator — Increase & Decrease Tool

Calculate screen width and height from diagonal size and aspect ratio. Convert between inches and centimeters for displays, TVs, and monitors with instant dimension calculations.

Calculate DPI (dots per inch), image dimensions, and print sizes. Convert between pixels and physical dimensions for printing and displays.

Generate time-based one-time passwords from a TOTP secret key. Enter your base32 secret, choose a period and digit length, and get the current and next codes with a live countdown timer. Useful for testing and debugging 2FA integrations.

Format, validate, and inspect JSON Lines (JSONL) and NDJSON files. Validates each line individually, reports parse errors by line number, outputs compact JSONL or a pretty-print preview, and lets you download the cleaned file.

Generate Zod validation schema code from a JSON sample object. Infers z.string(), z.number(), z.boolean(), z.array(), z.object(), and z.null() types automatically. Handles nested objects, arrays of objects with optional field detection, and outputs copy-ready TypeScript with import and z.infer type alias.

Calculate the information-theoretic bit entropy of any password or API key. Detects character set pools automatically, shows the total number of possible combinations, and estimates crack time across five attack scenarios from rate-limited web logins to GPU cracking clusters.

Check TLS protocol version compatibility and cipher suite strength ratings against current best practices. Supports IANA and OpenSSL cipher names — rates each suite as Strong, Weak, or Deprecated and explains why.

Scan pasted text, code, or config files for accidentally exposed API keys, tokens, passwords, and private keys. Detects 50+ secret types across AWS, GitHub, Stripe, OpenAI, and more — all client-side, nothing leaves your browser.

Full-featured scientific calculator with trigonometric, logarithmic, exponential functions, memory operations, and calculation history

Calculate grade point average from grades. Support multiple GPA scales (4.0, 5.0, 10.0), letter grade to GPA conversion, weighted/unweighted GPA, semester GPA and cumulative GPA tracking

Calculate final grade based on assignments and weights. Support multiple assignment categories (homework, quizzes, tests, final exam) with custom weights, show current grade and what's needed on remaining assignments

Calculate with fractions - add subtract multiply divide. Support all operations with automatic simplification to lowest terms, mixed number support, decimal conversion, and step-by-step solution display

Calculate standard deviation and variance. Support both population and sample statistics, paste data from Excel/CSV, show mean, median, variance, standard deviation, and complete statistical analysis

Calculate cumulative college GPA across multiple semesters. Track overall GPA, major GPA, and institutional GPA separately. Supports transfer credits, honors eligibility checking, and semester-by-semester breakdown

Calculate what score you need on your final exam to achieve your target grade. Enter your current grade, final exam weight, and desired grade to instantly see the required final exam score with achievability status

Calculate the square root of any number. Instantly shows the result, perfect square check, simplified radical form, and cube root.