Media
Extract audio from video and convert to FLAC (lossless) format
video-to-flacMedia
Extract audio from video and convert to Opus format
video-to-opusMedia
Extract audio from video and convert to MP3 with bitrate, resampling, and channel options
video-to-mp3Media
Extract audio from video and convert to WAV (PCM) with optional resampling and channel selection
video-to-wavFormat Conversion
Encode and decode text using Vigenère cipher with a keyword
vigenere-cipherHealth
Estimate VO2 Max based on activity type and performance data
vo2-max-calculatorUtilities
Test your typing speed with multi-difficulty English and Chinese text samples. Real-time WPM, accuracy, net speed, and per-character error breakdown.
typing-speed-testHealth
Predict the trough concentration Cmin from a measured peak concentration Cmax during therapeutic drug monitoring (TDM): Cmin = Cmax · e^(-kτ), where k = ln2 / t½ and τ is the time from the peak to the next dose. Inputs are the measured peak, the elimination half-life, and the dosing interval. Also reports the fraction of the peak remaining at the trough and the peak-to-trough drop. This tool takes a measured Cmax (the TDM workflow), unlike drug-half-life-dose (which derives C0 from Dose/Vd) and dosing-interval-designer (which outputs a dimensionless peak/trough ratio, not an absolute concentration). Valid for one-compartment first-order elimination with the peak measured post-distribution. Not medical advice.
trough-level-estimatorScience
Propagate a spacecraft/satellite state vector (r₀, v₀) to time t₀+Δt under two-body gravity via the universal-variable (f-and-g) method, and derive the classical orbital elements
two-body-state-vector-propagatorMath & Numbers
Convert common physical, chemistry, cooking, medical, and information units with the formula and dimensional analysis visible.
unit-converter-with-formulaFinance
Compare supermarket product prices by normalizing them to a common unit (per 100g, per liter, per piece, etc.). Enter products as 'name, price, quantity, unit' per line. Ranks from cheapest to most expensive per unit and shows savings vs the most expensive option.
unit-price-calculatorGames
Test your knowledge with a trivia quiz. Random questions from a built-in English bank across science, history, geography, and general topics. Pick 1 of 4; get your score and accuracy at the end.
trivia-quiz