Morse Code to Text

What this tool is used for

• Decoding a sequence written down by ear, where the letter and word gaps are the only structure available.
• Working out what a blinking light or a beeping pattern in a puzzle or a CTF challenge spells out.
• Checking a transcription against the intended message to find exactly where the spacing went wrong.
• Reading Morse embedded in an audio waveform after transcribing the dots and dashes visually.
• Verifying a sequence is valid Morse at all before assuming the transmission itself was garbled.

Frequently Asked Questions

How is the spacing interpreted?

Three levels, and getting them wrong is the main source of decode errors: one unit between elements of a letter, three units between letters (usually a space), seven between words (usually a slash or double space).

Can every Morse sequence be decoded?

Only with correct spacing. Without letter gaps the code is ambiguous — ...- - - is V then T T, or S then O, or several other readings. Morse is a prefix-free code only because of the timing, not the symbols.

What are prosigns?

Procedural signals sent as one run-together character: SOS is ...---... with no internal gaps, and is NOT S-O-S. Others include AR (end of message) and BT (paragraph break). Decoding them as separate letters is wrong.

Does Morse handle accented letters?

Partly. There are codes for a few, such as É (..-..) and Ä (.-.-), but no coverage for most scripts. Non-Latin languages use their own systems entirely, such as Wabun code for Japanese kana.

Is Morse still used?

Yes — amateur radio (where it is called CW), aviation navigation beacons that identify themselves in Morse, and as an accessibility input method for people with limited mobility. Maritime use officially ended in 1999.

What makes Morse ambiguous without correct spacing?

That it is not a prefix-free code — `...` is S, but it is equally E-E-E or I-E. Only the gaps separate them, which is why a stream with lost spacing has many valid readings and no way to choose between them.

How is a mistake corrected in transmission?

With eight dits in a row, the error prosign, followed by the word retyped from its start. There is no backspace, so the convention is to abandon the word rather than repair it mid-way.

What does a decoder do with an unknown sequence?

There is no universal answer — most output a placeholder rather than guessing, since a wrong character silently corrupts the message. Sequences longer than about six symbols usually indicate lost spacing rather than an exotic character.

Common errors and gotchas

• Using one space for both letter and word gaps, which turns a message into a single unreadable run of letters.
• Mixing separator styles — a slash for word breaks in one place, a double space in another — so the split comes out inconsistent.
• Transcribing a long dash as two dots when reading by ear, which quietly produces a different letter rather than an error.
• Expecting a prosign like SOS to decode as three letters. It is sent as one unbroken symbol with no letter gaps inside it.
• Assuming every sequence maps to something. Combinations longer than the standard set have no assigned character at all.