Morse as sound, in both directions. The text tool on this site handles the dots and dashes as characters; this one handles them as audio, keyed at a speed, and reads the audio back.
Text to Morse audio
Character speed is the words-per-minute rate in PARIS timing, where a dot is 1.2 seconds divided by the speed, a dash is three dots, and the gaps inside a letter, between letters and between words are one, three and seven. Farnsworth spacing below the character speed keeps the letters at full speed and stretches the gaps by the ARRL formula, so a learner hears real letters at a slower overall pace. Pitch and level set the tone; the keying has a short rise and fall so there are no clicks.
Morse audio to text
Open a recording, or listen with the microphone next to a receiver or a practice oscillator. The envelope of the tone is followed, marks and spaces are measured, the dot length is found by splitting the marks into two clusters, and the spaces are split the same way into letter gaps and word gaps. The decoded text and the measured speed appear as they are read.
Tone frequency
With the tone frequency at 0 the decoder follows the whole band, which is fine for a clean file. For a recording with hiss, hum or other signals, set the frequency of the tone and a band-pass of about a fifth of an octave is put in front of the envelope follower. Receivers usually put a Morse tone between 600 and 800 Hz.
Limits
Hand keying with uneven dots can confuse the clustering on a short message; longer messages measure better. Two stations at the same time cannot be separated. The character set covers letters, digits and the common punctuation and prosigns written as single characters.