A little closer, sign by sign.
Practise South African Sign Language with your webcam.
… signs · … lessons · … letter handshapes
Letters, one hand at a time.
Fingerspell to your webcam. Each letter is read while you hold it still.
Find the shape of your sentence.
Paste a sentence or a paragraph. Explore a suggested word order based on SASL lessons. Check the meaning and expression with your teacher.
Every sign, on a card.
The whole Real SASL reference. Watch any sign, or add it to your lesson.
How it works, and how well.
What it measures, what it cannot do, and whose work it stands on.
Your camera Camera off
Ready when you are.
Keep your face, shoulders and hands in frame. Sit back far enough that all three show.
Before you record
- Light in front of you, not behind.
- Sit back until your raised hands show.
- Start and finish with your hands resting.
Before you spell
- One hand, palm towards the camera.
- Hold each letter still for a moment.
- Keep your hand near the middle of the picture.
Lesson … change lesson
-
Watch
—
Drawing the signer…
Drawn from the dictionary clip -
Sign
With the camera on, raise your hands and sign once. Rest your hands to see the guess. Automatic recognition is on by default; Record and Space are optional.
-
See how you did
-
Sign
Sign any word from your lesson and this names it.
Raise your hands and sign. Pause briefly between signs, then rest your hands to see the result.
-
What it looked like
-
Sign to me
Sign a few words, with a short pause between signs, then rest your hands. Each sign is read, the likeliest sequence is chosen, and it is turned back into English.
-
What I understood
Nothing yet. Start the camera and sign to it.
-
Sign a phrase
Sign two to five words from your lesson, with a short pause between them. Each sign is read on its own: this checks which signs you made, and in what order.
It does not translate. SASL grammar lives in space, facial expression and how signs are changed, and none of that is interpreted here.
-
The signs it found
Spell this word
Next letter
Spell anything
Hold each letter still. Hold on, or change shape, to repeat a letter.
Watch
The drawn signer, then the Deaf signer on Real SASL.
Sign
Sign it to your camera, once.
See how you did
Matched, close or not yet, and your try beside the reference.
Contents
Lessons
Each lesson is a short list of signs. Your tries are compared with that list, so the shorter it is, the more reliable the answer.
NID from the National Institute for the Deaf’s sign charts.
In this lesson
…
Plate I — the SASL manual alphabet
Right hand, as you see it facing the signer · J and Z move · tap a hand to enlarge it
Letters worth a second look
- T — fold your index finger down over the tip of your thumb. The American T, with the thumb poking out between index and middle finger, is not the South African one; every SASL presenter this learned from uses the folded index.
- Y — thumb and little finger out, as in ASL.
- U, V, R — two fingers up: together, apart, or crossed.
- G and H — pointing sideways with one finger, or with two.
- P and Q — the K hand and the G hand, turned to point down.
- J and Z are drawn in the air: the I hand draws a J, the index finger a Z. The camera reads them from the fingertip's path, not a held shape, so draw them clearly and not too fast.
Dictionary · A–Z
How it works
What this does
Your camera feed goes through hand, body and face tracking on this device. A recorded sign becomes a sequence of points, and two families of pretrained sign models describe it in a way that ignores who is signing. That description is compared with 3,483 reference clips of 1,858 signs from the Real SASL dictionary and the National Institute for the Deaf's SASL Video Dictionary. Nothing is uploaded, and there is nothing to set up: it was built to work for someone it has never seen.
How well it works
Measured on signers the models had never seen, never on the data they learned from:
- 96%Fingerspelling. Held letters read correctly, tested on each of five SASL presenters in turn after training on the other four.
- 82%A 10-word lesson. The top answer is right 82% of the time, and the right word is in the top three 96% of the time.
- 3 in 10The whole dictionary. That is why practice happens in lessons: the smaller the list, the more reliable the answer.
- 82%The quiz. Sign the word asked and it says “matched” 82% of the time and “close” 15%; sign an unrelated word and it wrongly says “matched” about one time in twenty.
Limits
What it does not do
- It is not a translator. No system can yet translate signed language from a webcam, and this one does not try.
- A match is not a grade. “That looked like FRIDAY” is not the same as “that was a perfect FRIDAY”. Your teacher is the judge of that.
- Facial grammar is not judged. Facial expression, eyebrows and the use of space carry SASL grammar. The face is tracked as part of a sign’s shape, but none of that grammar is interpreted.
- SASL varies. Signs differ between regions and schools. If your course teaches a different version from Real SASL, trust your course.
Where it comes from
- Reference signs: Real SASL. The app keeps only numbers derived from the clips (the tracked movement of the body, hands and face outline) and links to the site for the videos.
- Letters learned from SASL alphabet videos by the National Institute for the Deaf, The Sign Tutors, and three other presenters, every example checked by hand; and from ASL-HG (Mendeley Data, CC BY 4.0) for the letters SASL shares with ASL.
- Sign models: SignCLIP (Jiang et al., 2024) and OpenHands (AI4Bharat). Tracking: MediaPipe.
- Drawings: made for this app — the letter hands are traced from real, hand-checked frames; the plants and mountains are drawn by code. The drawn signer is made from the points tracked in each Real SASL clip: an illustration of the movement, not the video, so it always links the original.