UD5 Toolkit
Online Hearing Test – Frequency Pitch Perception
Play pure tones at various frequencies to estimate your hearing range. Simple and educational.
Tag: Word Frequency Counter - Analyze Text
16+ toolsCharacter Frequency Analyzer - Online Visual Heatmap of Text
Analyze letter/symbol frequency with an interactive bar chart and heatmap. Useful for breaking simple ciphers, linguistics, and SEO keyword analysis. Local processing.
Virtual Dog Whistle – Online Adjustable Frequency Tone
Play a sine wave tone adjustable from 5kHz to 22kHz. Test your hearing and your dog's attention.
Online Hearing Range Test – Frequency Sweep Hz
Play a frequency sweep from 20Hz to 20kHz. See where your hearing cuts off. Headphones needed.
Electromagnetic Spectrum Explorer - Online Wavelengths
Zoom through the electromagnetic spectrum from radio waves to gamma rays. See wavelength, frequency, and applications. Static educational page.
Drum Shell Fundamental Note Calculator – Online Bearing Edge
Enter drum diameter, depth, and material to find the shell's approximate fundamental note. For tuning reference.
Antenna Length Calculator - Online 1/4 Wave & Dipole Tool
Calculate antenna element lengths for a given frequency (or vice versa). Supports 1/4 wave, 1/2 wave, dipole. Useful for ham radio. Local only.
Analyser Node Playground - Online Real‑Time Frequency & Waveform
Connect an audio source to an Analyzer Node and display frequency and time‑domain data. Learn Web Audio visualization.
Letter Frequency Analyzer - Online ETAOIN SHRDLU
Paste text to see a live letter frequency bar chart. Helps break substitution ciphers. All local analysis.
Character Frequency Chart - Online Text Analysis
See a live bar chart of character frequencies as you type or paste text. Great for cipher cracking and linguistics.
Online Spectrogram Viewer - Audio Frequency Visualizer
Load an audio file and see its spectrogram with frequency over time. Adjust resolution and color map. Discover hidden sounds.
Image FFT Visualizer - Online See Frequency Domain
Upload an image and see its 2D FFT magnitude and phase. Learn how image filtering works. Educatinal tool. Canvas.
MIDI Note to Frequency Converter - Online Music Tuning
Enter a MIDI note number (0–127) or a musical note name and get the exact frequency in Hz. Piano keyboard picker.
Online Tone Generator - Audio Frequency & Sound Wave Tool
Generate pure audio tones of specific frequencies (Hz). Adjust waveform type (sine, square, sawtooth). Ideal for audio testing and science experiments.
Live Sound Frequency Detector - Online Audio Analyzer
Use your microphone to detect the dominant frequency of ambient sounds. Visualize the spectrum. Local Web Audio.
Character Counter - Online Letter & Symbol Frequency Tool
Deep-dive into text with detailed character and letter frequency analysis. Supports multiple languages and includes whitespace control. Fast and private.