CaptchaKraken Sunlight (AWQ 4-bit)

A standalone captcha-solving model: the CaptchaKrakenV1_Lora adapter merged into Qwen/Qwen3.5-9B and quantized to AWQ 4-bit. One download, no adapter to wire up.

Sunlight is the lighter of two hardware tiers. Twilight is the same adapter and base at FP8, ~5 GB larger and ~4 points stronger.

  • Weights: ~9.1 GB · Min VRAM: ~11 GB
  • Base revision: c202236235762e1c871ad0ccb60c8ee5ba337b9a
  • Quantized: language-model linears at 4-bit (group 128, asymmetric). The vision tower, the linear-attention projections and the multi-token-prediction head stay bf16 — quantizing those costs accuracy out of proportion to the space saved. Calibrated on 256 in-domain captchas (hCaptcha + reCAPTCHA, none from the held-out set).
  • Solves: reCAPTCHA and hCaptcha grids, plus hCaptcha drag / click / path / fit puzzles.

Serving (vLLM)

vllm serve CaptchaKraken/Sunlight-AWQ-4bit \
  --max-model-len 8192 --gpu-memory-utilization 0.85 --trust-remote-code --port 8000

No --enable-lora and no adapter flags — the adapter is already merged in.

Prompts — read this before integrating

This model only performs as measured when it is sent the prompts it was trained on. prompts.json in this repo carries them, along with the puzzle-type → template mapping and a prompt_version. Resolve prompts from that file rather than hardcoding a copy: a mismatched prompt does not error, it silently collapses accuracy.

Two integration requirements:

  • Disable thinking. Send chat_template_kwargs: {"enable_thinking": false}. With thinking on and a qwen3 reasoning parser, the answer is routed into reasoning and content comes back empty.
  • Coordinates are normalized 0–1000, top-left (0,0), bottom-right (1000,1000) — not pixels.

Evaluation

Scored with the project's soft-tolerance grader on 156 human-labelled held-out captchas, through an OpenAI-compatible vLLM endpoint. Samples promoted into the labelled-train pool are excluded, so nothing here was trained on. Grid puzzles are exact tile-set match with per-error decay; click/drag receive partial credit by normalized distance — so these are graded scores, not "percent solved".

model score
Twilight (FP8) 66.87%
production captcha (FP8 base + LoRA at serve time) 66.30%
Sunlight (AWQ 4-bit) 62.72%

Merging costs nothing: Twilight matches the served base+adapter setup within noise. The 4-bit gap concentrates in coordinate-precision puzzles (drag, path) rather than tile selection, where the two are identical.

License

CaptchaKraken Source-Available License v1.0 — see LICENSE.

Use it, modify it, build commercially on it where captcha solving is an internal component of a product that delivers value beyond the solve — scrapers, anti-detection browsers, automation frameworks, QA and accessibility tooling.

You may not sell the solve: no reselling or offering for a fee a captcha solving service or API whose primary value is solving captchas, no thin wrappers exposing this model's solving capability, and no relaying its outputs through a paid or public captcha-solving API. Those require a separate written commercial agreement.

Copyright (c) 2026 CaptchaKraken LLC. All rights reserved.

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