Morse Code Decoder

Decode typed Morse code

Put a space between letters and a slash (/) between words. The decoder also reads a vertical bar (|), a line break or 3 or more spaces as a word gap. Look-alike characters such as • or · for a dot and _ for a dash work too.

A run of dots and dashes that isn't in the alphabet shows as # in the text, and the codes are listed under the box so you can find the typo. The most common cause is a missing space that joins two letters into one long code.

...---... with no gaps decodes as SOS, since the distress signal is sent as one unbroken run. Decoded text is always in capitals, because Morse code has no lowercase.

Decode Morse code from an audio file

Press Upload a recording or drop a file on the panel. Any audio or video file your browser can open works, such as WAV, MP3, M4A, OGG or WebM, up to 50 MB. The decoder reads the first 10 minutes and mixes stereo down to one channel.

It looks for the strongest steady tone between 250 and 1,800 Hz, learns the speed from the signal itself, and shows the tone, the WPM and the length. Recordings sent with Farnsworth spacing decode too. The file is read on your device and never uploaded.

Decode Morse code with your microphone

Press Use microphone and allow access when your browser asks. Hold your phone or laptop near the speaker. The decoder rereads what it has heard every half second, so the Morse code box fills in and corrects itself as it goes. Press Stop when the message ends.

Noise suppression, echo cancellation and automatic gain are turned off while it listens, because they tend to treat a steady tone as noise and remove it. The sound is processed in memory only; it is never recorded, saved or sent.

How to get a cleaner decode

A cleaner recording gives a better decode. These help:

• Record one signal at a time. Two stations at once confuse it.
• Get close to the speaker and keep the room quiet.
• Upload a file when you have one. A direct recording is cleaner than sound picked up through the air.
• Trim talking or music before and after the code.
• If a letter looks wrong, fix it in the Morse code box. The text updates at once.

What it can't decode well

The decoder is tested on recordings from 10 to 30 WPM and 440 to 800 Hz, including noisy ones. It has trouble with:

• Hand-sent code with very uneven timing.
• Several signals at once, such as a busy radio band.
• Heavy noise or static.
• A tone that drifts up and down in pitch.
• Morse code mixed into speech.

How the audio decoder works

It works in four steps, all in your browser. If it finds no tone at all, for example in pure noise, it says so instead of guessing.

1. Find the tone: the strongest steady pitch between 250 and 1,800 Hz.
2. Follow its loudness over time and split it into sound and silence.
3. Learn the speed from how long those stretches last.
4. Read short sounds as dots and long ones as dashes, and use the length of each silence to tell a letter gap from a word gap. The code then decodes like typed code.