Cobalynx answers with evidence: paste text for a calibrated
probability with published error rates — never a guess — or check a
file's provenance credentials. No signup, no interstitials.
You're in the queue
Your scan starts automatically — keep this page open. Estimates come
from the current measured processing speed.
A “likely AI” verdict is probabilistic evidence, not proof. False positives happen; never treat this result alone as grounds to accuse a writer.
AI-text detectors as a class are more likely to false-flag writing by non-native English speakers. Cobalynx measures and publishes its error rate on non-native (ESL) writing and holds it to the same gate as every other register.
No AI-text detector is fully reliable, including this one. In line with EU AI Act transparency guidance, Cobalynx publishes its measured error rates and reports calibrated probabilities, never certainty.
File provenance result
File checked
What the credentials say
Metadata signals — weak evidence
Document metadata is typed by software and trivially editable. These
signals can hint at the tool that touched a file; they can never prove
how its words were written.
Technical details
Provenance evidence is asymmetric: verified Content Credentials are strong evidence about a file's origin, but missing credentials or clean metadata prove nothing — most files have neither, however they were made. Never treat an empty result as proof of human authorship.
No AI-text detector is fully reliable, including this one. In line with EU AI Act transparency guidance, Cobalynx publishes its measured error rates and reports calibrated probabilities, never certainty.
What our verdicts mean
Measured in one sanctioned run on a frozen held-out evaluation set —
clean, non-native and adversarial slices together, so paraphrase-attacked
and older AI text weighs on these rates
(August 16, 2026; every run of the measurement is
disclosed in the ledger), abstentions
included:
When we say likely AI, the text was actually human
0.7%
of the time
(3 of 442;
statistical upper bound 2.0%).
When we say likely human, the text was actually AI
26.9%
of the time
(223 of 829;
statistical upper bound 30.0%).
We answer inconclusive — and say so, instead of guessing —
on 16.5%
of that evaluation set
(251 of 1522).
Measured accuracy, published
We evaluated the detector in one sanctioned run on a frozen held-out
set and committed the results — error rates with confidence
intervals, not a marketing number. Every figure on this site traces
back to that measurement, and every execution of the measurement
command is disclosed in an append-only run ledger.
Some providers watermark their text; most do not. We track who
actually does — and we will never claim to detect a watermark that
was never embedded. Nobody can.
A wrong “AI” verdict can cost a student or writer dearly. That is why
we refuse texts too short to judge, show a calibrated probability
instead of a confident label, and abstain when the evidence is thin.
Already been flagged by another tool?
Start here.
Score. Multiple independent signal families —
statistical and learned — score your text as a whole and section by
section; the per-section scores are what the heatmap bands show.
Calibrate. Raw scores are calibrated against measured
outcomes, so the probability you see means what it says.
Report — or abstain. Clear cases get a verdict with a
probability; borderline cases are reported as inconclusive, not guessed.
Provider states as reviewed on August 16, 2026 (served live by the detection service):
GoogleannouncedSynthID-Text published by Google DeepMind (Nature 2024, open-sourced detector code), and deployed in Gemini — but no public verification API is available for third parties, so no adapter can go live.
AnthropicannouncedAnthropic announced (Aug 11-14, 2026) that Claude models launched after Aug 2, 2026 watermark their text output; its detection API is announced but not yet public, so no adapter can go live.
OpenAIunavailableOpenAI built a text watermarking method internally (reported 2024) but has not released it or any verification API; pending.
MetaunavailableMeta published watermarking research (e.g. video/audio; Three Bricks for text) but ships no public text watermark verification; pending.
MistralunavailableNo announced text watermarking or verification API from Mistral; pending.
MicrosoftunavailableMicrosoft backs C2PA for media provenance but exposes no text watermark verification API; pending.
xAIunavailableNo announced text watermarking from xAI.