Voight

Voight is the CAPTCHA replacement humans never see. It tells bots and AI agents apart from people using proof-of-work, behavioral, and fingerprint signals — with zero clicks, puzzles, or traffic lights for real users.

reCAPTCHA, hCaptcha, and Turnstile tax every real user with image grids and checkboxes to stop a minority of bots, hurting conversion and accessibility. Voight stays invisible to humans while still building a record of who is actually a bot. Drop the /check/challenge widget where your CAPTCHA used to sit, issue a challenge with POST /v1/challenge, and verify on submit with POST /v1/challenge/verify — real users see nothing.

When to use it

Use Voight anywhere you would reach for a CAPTCHA — signup, login, contact, checkout — but do not want to interrupt real people. It binds to your form_id and origin like a reCAPTCHA site key, but never shows a checkbox or an image grid. Because it is capture-only in beta, today it is a way to build a labeled bot/human corpus from your own traffic without touching conversion, and to have enforcement wired up the day the verdict ships.

How it works

1. Issue a challenge

   Call POST /v1/challenge to mint a single-use nonce, a binding token, and an ALTCHA-style proof-of-work. The embeddable /check/challenge widget solves the proof-of-work in the background and captures interaction telemetry — no checkbox, no image grid, nothing the user has to do.

2. Verify on submit

   On form submit, call POST /v1/challenge/verify with the solved proof-of-work, the token, and the nonce. The nonce is single-use, so a replayed or forged challenge is rejected. The captured pointer, scroll, and timing trajectory is recorded for the bot/human model.

3. Read the capture summary

   verify returns a compact summary — pow_valid, token_valid, solve time, interaction counts, and a challenge_id. In beta this is capture-only: every request passes while the verdict calibrates, so you wire it in now and switch on enforcement when the model is ready.

Quickstart

Issue a challenge, let the widget solve the proof-of-work and capture telemetry, then verify on submit. The widget and the issue call need only your publishable key; verify is a server-side call with your API key.

1. Issue a challenge

curl -X POST https://api.formshield.dev/v1/challenge \
  -H "Authorization: Bearer $FORMSHIELD_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "form_id": "signup" }'

You get back a single-use nonce, a binding token, and an ALTCHA-style proof-of-work for the browser to solve. The /check/challenge widget does this for you and solves the proof-of-work in the background.

2. Verify on submit

On form submit, send the solved proof-of-work, the token, the nonce, and the captured voight telemetry to POST /v1/challenge/verify.

curl -X POST https://api.formshield.dev/v1/challenge/verify \
  -H "Authorization: Bearer $FORMSHIELD_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "form_id": "signup",
    "token": "fs2.eyJ...",
    "nonce": "n_8f3a91c2",
    "pow_solution": { "challenge": "a1b2c3...", "salt": "d4e5f6", "number": 18244, "signature": "9c7e...", "took": 62 },
    "voight": { "t0": 0, "ts": 1840, "tgt": [220, 140, 18], "ptr": [[12,40,210,0]], "scr": [], "key": [], "pow": { "d": 18244, "ms": 62 } }
  }'

Response:

{
  "version": "1",
  "data": {
    "passed": true,
    "pow_valid": true,
    "token_valid": true,
    "solve_ms": 62,
    "duration_ms": 1840,
    "n_pointer": 1,
    "n_scroll": 0,
    "target_hit": true,
    "challenge_id": "vgt_3f9a2c71b840"
  },
  "error": null,
  "metadata": { "credits": 1 }
}

The signals

Voight fuses several independent signals so no single tell decides the verdict. Each is one input to the bot/human model, never a standalone human/bot gate.

Verify fields

The verify response is a compact capture summary. Each verify costs 1 credit; issuing a challenge is free.

Endpoints

Common questions

Next steps