Real-Time FFT · Web Audio API · No Registration · 100% Free

Frequency Analyser for Mixing Free Online Frequency Checker

The most advanced free online frequency analyser for mixing, mastering, and audio diagnostics. Real-time FFT spectrum from 20 Hz (bass, left) to 20 kHz (treble, right) — visualize every frequency in your audio instantly. Height indicates loudness. Hover to see exact frequencies. No registration, no download, no cost.

Used by music producers, sound engineers, acoustic consultants, and audiophiles for live spectrum analysis, EQ reference, room acoustics measurement, microphone frequency response testing, and 50/60 Hz hum detection. 100% free online, no registration required — works in Chrome, Edge, Firefox, Safari.

📊 Real-Time FFT Spectrum 🎤 Mic / Line Input 📈 20Hz–20kHz Range 🎚️ 10-Band Octave EQ 〰️ Oscilloscope Waveform 🟣 Spectrogram 🎵 Note Detection ✅ 100% Free 🔒 No Registration ⚡ Instant Results

Live Frequency Analysis Tool — Real-Time FFT Spectrum Analyser

Free Online Frequency Analyser

Click Start Analyser and allow microphone access. Frequencies run from 20 Hz (bass, left) to 20 kHz (treble, right). Bar height indicates loudness in dB. Hover the spectrum to see exact frequency and amplitude. All processing is 100% local, no audio data sent anywhere. Free, no registration.

FREQUENCY ANALYSER — REAL-TIME FFT SPECTRUM · FREE ONLINE

⏸ IDLE FFT 4096 WEB AUDIO API NO REGISTRATION

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Start Free Online Frequency Analysis — No Registration Required

This free frequency analyser uses your microphone to perform real-time FFT spectrum analysis from 20 Hz to 20 kHz. All audio processing is local — nothing is recorded or sent to any server. 100% free, no login needed.

1Click "Start Analyser" above

2Allow microphone permission

3Real-time spectrum appears instantly

Chrome · Edge · Firefox · Safari · No download · No registration · 100% free · No software needed

Peak Freq

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Peak dBFS

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RMS Level

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Nearest Note

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Centroid

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Sample Rate

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FFT Bins

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FFT Size

Smoothing

Display Mode

Freq Scale

Color Theme

Gain 0 dB

Min dB -100

20Hz50Hz100Hz200Hz500Hz 1kHz2kHz5kHz10kHz20kHz

Sub BassBassLow MidMidHigh MidPresenceBrillianceAir

Waveform Oscilloscope — Time Domain

Live

Spectrogram — Frequency vs Time (scrolling)

Time →

10-Band Octave Spectrum Analyser — Industry Standard Bands

Stereo L/R VU Meters Peak: —

Left

Right

Signal Meters

RMS LEVEL—

PEAK HOLD—

SPECTRAL CENTROID—

BASS ENERGY—

Top 8 Peak Frequencies — Auto-Detected

#	Frequency	Amplitude (dBFS)	Band	Nearest Note	Harmonic
Waiting for audio signal — make some sound or play audio near microphone...

00:00

Recording in progress — all frequency peaks being tracked

What This Free Tool Does

The Most Advanced Free Online Frequency Analyser Available

Our free online frequency analyser delivers professional-grade real-time FFT spectrum analysis from 20 Hz to 20 kHz — with octave band analysis, waveform oscilloscope, scrolling spectrogram, VU meters, peak detection, note identification, and audio recording. No registration, no download, no cost. More features than any other free online frequency checker.

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Real-Time FFT Spectrum Display

Uses the Web Audio API AnalyserNode to perform Fast Fourier Transform on your live audio signal, converting it from time domain to frequency domain — showing exactly which frequencies are present and how loud each one is, updated 60 times per second. Frequencies from 20 Hz (bass, left) to 20 kHz (treble, right). Height indicates loudness.

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Scrolling Spectrogram Display

A scrolling spectrogram shows frequency content over time — a 2D heat map with time on the horizontal axis, frequency on the vertical axis, and colour intensity representing amplitude. Essential for analysing sustained tones, room resonances, and how frequency content evolves as audio plays.

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Waveform Oscilloscope

A live time-domain waveform oscilloscope displays raw audio wave cycles, clipping, DC offset, and transient behaviour. Critical for diagnosing distortion, checking microphone preamp quality, verifying clean signal chain operation, and identifying asymmetric waveform distortion.

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10-Band Octave Analyser

Industry-standard 10-band ISO octave spectrum analyser showing energy across sub bass (31 Hz), bass (63 Hz), low mid (125 Hz), mid (250 Hz), upper mid (500 Hz), presence (1 kHz), upper presence (2 kHz), brilliance (4 kHz), air (8 kHz), and ultra high (16 kHz) — matching professional graphic EQs.

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VU Meters & Signal Analysis

Real-time VU meters, RMS level meter, peak hold display, spectral centroid tracker, and bass energy meter give you a complete picture of your signal's dynamic and spectral characteristics in one view — tools usually found only in expensive professional DAW plugins.

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Musical Note Detection Free

Identifies the nearest musical note to your strongest detected frequency across all octaves from C0 to C8, including cent deviation. Essential for instrument tuning, identifying tonal resonances, checking microphone proximity effect, and verifying the fundamental pitch of audio signals.

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Top 8 Peak Frequency Detection

Automatically identifies the 8 strongest peaks in your spectrum with their exact frequency, amplitude in dBFS, band classification, nearest musical note, and harmonic relationship to the fundamental frequency. Peaks highlighted visually on the spectrum display with colour-coded markers.

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5 Display Modes

Switch between Bar Spectrum, Line Spectrum, Filled Wave, Mirror Spectrum, and 3D Bar modes. Five colour themes: Rainbow Spectrum, Orange Glow, Matrix Green, Deep Blue, and Monochrome. All visualize the same frequency data differently to suit different analysis and aesthetic preferences.

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Export Data & Record Audio Free

Download a complete spectrum data report as a text file, or record your audio session directly in the browser and download as a WebM audio file. Export includes all peak frequencies, octave band levels, RMS level, spectral centroid, FFT settings, and timestamp. All free, no registration.

Frequency Band Reference Guide

Understanding the Audio Frequency Spectrum

The full human hearing range spans 20 Hz to 20 kHz. Use this free online frequency checker to identify and address each band in your audio — no registration required. The spectrum is divided into distinct regions, each with unique sonic characteristics critical for mixing and mastering decisions.

Band	Range	Characteristics	Common Sources	Mixing Tips
Sub Bass	20–60 Hz	Felt more than heard; power and weight	Kick drum sub, bass synth, pipe organ	Cut below 30 Hz on most tracks; boost carefully on kicks only
Bass	60–250 Hz	Warmth, fullness, and body of a mix	Bass guitar, kick drum, male vocals, cello	Muddiness lives here — cut overlapping instruments to separate
Low Mid	250–500 Hz	Warmth vs boxiness; fundamental clarity	Guitar body, piano lower register, brass	Most congested area in a mix; strategic cuts improve clarity
Mid	500Hz–2 kHz	Presence of instruments; nasal quality	Vocals, snare, guitars, keys fundamental	Boost for presence; cut to reduce nasal or honky character
Upper Mid	2–4 kHz	Attack, definition; peak ear sensitivity	Vocal sibilance, guitar attack, hi-hat edge	Human ear most sensitive here — boost sparingly for clarity
Presence	4–6 kHz	Articulation, clarity, cut-through	Vocals, percussion crack, acoustic guitar	Boost for forwardness in a mix; cut to push elements back
Brilliance	6–12 kHz	Brightness, shimmer, sparkle	Cymbals, hi-hat, vocal air, acoustic guitar	Shelf boost for energy and life; cut if harsh or sibilant
Air	12–20 kHz	Openness, space, room ambience	Room sound, mic self-noise, top end sheen	High-shelf boost adds air; cut controls harsh digital treble

Who Uses This Free Online Tool

Free Frequency Analyser Use Cases

This free online frequency checker is used by professionals and hobbyists across music production, acoustic engineering, broadcast audio, education, and live sound — no registration required for any of these applications.

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Music Mixing & Mastering

Identify frequency clashes between instruments, check mono compatibility, verify low-end balance, and ensure your master translates across systems using this free real-time spectrum analyser. No registration needed.

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Microphone Testing Free

Test the frequency response of any microphone online for free — identify which frequencies your mic emphasizes or cuts, compare different mics, detect proximity effect buildup in low frequencies.

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Room Acoustic Measurement

Identify room modes and resonant frequencies in your studio. Play pink noise through speakers and use this free analyser to spot room-induced peaks and nulls without expensive measurement software.

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Instrument Tuning & Harmonics

See the fundamental frequency and harmonic series of any instrument in real time. Check tuning accuracy, identify inharmonicity, and visualize overtone content that shapes timbre.

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Speaker System Testing

Test speaker frequency response free online using a measurement microphone. Identify crossover points, cabinet box modes, and horn resonances without dedicated hardware analyzers.

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Audio Education & Learning

Perfect for audio engineering students learning FFT analysis, harmonics, and EQ. Sing a note and watch the fundamental and harmonics appear in real time — completely free, no registration.

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Broadcast Audio QC

Check audio for broadcast standards — verify no sub-20 Hz rumble, check for 50/60 Hz hum, identify HF rolloff, ensure programme material meets broadcast frequency guidelines.

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Streaming & Gaming Audio

Optimise your streaming microphone. Check for hum, background noise, and mic resonances. Use this free frequency checker to ensure your audio is professional before going live.

Step-by-Step Guide

How to Use the Free Online Frequency Analyser

Getting your free real-time frequency analysis running takes under 15 seconds. No registration, no software, no download. Here's exactly what happens step by step when you use this free online frequency checker.

Click Start Analyser

Click the Start Analyser button to initiate the Web Audio API connection. Your browser will prompt you for microphone access — this is required for frequency analysis. All audio is processed locally; no audio data ever leaves your device. Completely free.

Allow Microphone Permission

Click Allow in the browser permission dialog. The analyser connects to your default microphone or audio interface. For professional room analysis, use a quality measurement microphone. For basic analysis, any built-in mic works. No registration required.

Real-Time FFT Begins

The Web Audio API AnalyserNode begins processing the signal using Fast Fourier Transform. The FFT converts the time-domain audio waveform into frequency-domain data — showing which frequencies from 20 Hz to 20 kHz are present and at what amplitude level.

Read the Spectrum Display

The main spectrum shows frequencies from 20 Hz (bass, left) to 20 kHz (treble, right) on a logarithmic scale matching how human hearing works. Bar height indicates loudness. Hover anywhere on the spectrum to see exact frequency and amplitude at that point.

Adjust FFT Resolution

Change FFT size using the dropdown — higher sizes give finer frequency resolution for detailed harmonic analysis; lower sizes respond faster to transients. Adjust smoothing to control display responsiveness. Gain control boosts quiet signals for better visibility.

Check All Display Panels

Review the waveform oscilloscope for time-domain signal health, the scrolling spectrogram for frequency-over-time patterns, the 10-band octave analyser for EQ balance, VU meters for level, and the peak frequency table for automatic top-8 peak identification.

Switch Display Modes

Change between Bar Spectrum, Line Spectrum, Filled Wave, Mirror Spectrum, and 3D Bar modes. Switch between 5 colour themes. Choose logarithmic or linear frequency scale. All changes happen in real time without interrupting the live analysis.

Export Your Free Data

Click Export Data to download a complete text report with all peak frequencies, octave band levels, RMS level, spectral centroid, and FFT settings. Or use Record to capture audio directly — download as WebM. All features free, no registration ever required.

Frequently Asked Questions

Free Online Frequency Analyser FAQ

Everything you need to know about using this free online frequency checker for mixing, acoustic measurement, and audio analysis. No registration required.

What is a frequency analyser and how does it work?

A frequency analyser — also called a spectrum analyser or FFT analyser — is a tool that shows the frequency content of an audio signal in real time. It uses the Fast Fourier Transform (FFT) mathematical algorithm to convert audio from a time-domain waveform into a frequency-domain spectrum, displaying which frequencies from 20 Hz (bass, left) to 20 kHz (treble, right) are present and how loud each is. Height indicates loudness in dBFS. Our free online version uses the browser's Web Audio API AnalyserNode — no plugins or registration needed.

Is this frequency checker really 100% free with no registration?

Yes — completely free, always, with no registration, no account, no email, no subscription. Every feature including real-time FFT spectrum, spectrogram, waveform oscilloscope, VU meters, 10-band octave analyser, peak detection, note identification, audio recording, and data export is available at zero cost. All audio processing happens in your browser — we never receive, store, or transmit your audio data. No registration required now or ever.

How accurate is this free online frequency analyser for professional mixing?

At FFT size 8192 with a 48 kHz sample rate, this free analyser achieves approximately 2.9 Hz frequency resolution per bin — sufficient for professional mixing reference and EQ decisions. At 16384 FFT (maximum setting), resolution reaches ~1.5 Hz/bin. For absolute calibrated measurements (acoustic engineering reports, speaker certification), dedicated hardware with calibrated measurement microphones is recommended. For mixing, EQ reference, room analysis, and educational use, accuracy matches dedicated software like SPAN, RTAV, or Voxengo. Accuracy depends heavily on your microphone's frequency response quality.

What does "frequencies run from 20 Hz to 20 kHz" mean for mixing?

The human hearing range spans approximately 20 Hz (the lowest audible bass frequencies — sub rumble, kick drum sub) to 20 kHz (the highest treble frequencies — air, shimmer, the very top of cymbals). In our free frequency analyser, 20 Hz is displayed on the far left of the spectrum and 20 kHz on the far right, on a logarithmic scale that matches how human pitch perception works. Most adult listeners lose sensitivity above 15–16 kHz over time. The most critical mixing frequencies are in the 80 Hz–8 kHz range where nearly all musical content lives.

Can I use this free tool to detect 50Hz or 60Hz mains hum?

Yes — this is one of the most common free uses. Start the analyser and look at the 50 Hz or 60 Hz region (depending on your country's mains frequency — 50 Hz in UK/Europe/Asia, 60 Hz in USA/Canada). Mains hum appears as a sharp, narrow vertical spike that stays constant regardless of audio content. You'll also often see harmonics at 100/150/200 Hz (50 Hz systems) or 120/180/240 Hz (60 Hz systems) getting progressively quieter. Solutions include balanced connections, proper grounding, better shielding, or a ground loop isolator.

What is the spectrogram display and how do I read it?

The scrolling spectrogram is a 2D time-frequency display where time moves from left to right, frequency runs vertically (20 Hz bottom to 20 kHz top), and colour intensity represents amplitude — brighter/warmer colours indicate higher amplitude. Unlike the FFT spectrum which shows a single instant in time, the spectrogram reveals how frequency content changes over time. This makes it invaluable for analysing sustained tones, room modes that ring after a sound stops, vibrato on vocals, and how transients evolve. It's the same display used in professional audio analysis software and acoustic measurement systems.

What is the difference between logarithmic and linear frequency scale?

Logarithmic scale matches how human hearing perceives pitch — an octave always takes equal visual width (100–200 Hz takes the same space as 8–16 kHz). This is the standard in music production, mixing, and mastering. Linear scale allocates equal visual space to equal frequency intervals — so most of the display is wasted on the 10–20 kHz range while bass is compressed into a tiny sliver on the left. Linear scale is used in engineering contexts for electronic signal analysis. For all music work, use logarithmic. Our free frequency analyser defaults to log scale with a one-click switch to linear.

Can I use this free frequency analyser to measure room acoustics?

Yes — play pink noise or a logarithmic sine sweep through your studio speakers, position a measurement microphone at your listening position, and run this free online frequency analyser. Room modes appear as prominent narrow peaks (resonances) and nulls (cancellations) in the bass and low-mid regions, typically below 300 Hz. Room modes are determined by room dimensions — a 4-metre room length creates a mode at approximately 43 Hz, for example. The scrolling spectrogram is particularly useful for room acoustic analysis as it shows how long resonances ring after the source sound stops.

What is the spectral centroid shown in the meter?

The spectral centroid is the weighted mean frequency of the spectrum — the "centre of mass" of all frequencies weighted by their amplitude. A high spectral centroid (e.g., 4–8 kHz) indicates a bright, treble-heavy signal; a low centroid (e.g., 200–500 Hz) indicates a warm or bass-heavy signal. It's used in psychoacoustics and audio analysis as a measure of perceived "brightness" or "timbre brightness". In mixing, monitoring the spectral centroid over time helps ensure your mix doesn't drift too bright or too dark compared to professional reference tracks. Our free online frequency analyser displays this metric in real time.

What browsers support this free online frequency analyser?

This free frequency analyser uses the Web Audio API AnalyserNode supported by Chrome 35+, Firefox 25+, Safari 14.1+, Edge 79+, and Opera 22+. Chrome and Edge on desktop deliver the best performance for maximum FFT sizes (16384). Mobile browsers work but may have limited FFT performance on older devices — use a desktop for professional analysis. No plugins, no Java, no Flash, no extensions required. No registration on any supported browser. For analysing computer playback instead of microphone input, enable "Stereo Mix" in Windows sound settings or use a virtual audio cable.