Stop overthinking.
Start untangling.
Cortex is a journaling app with an AI co-pilot trained on peer-reviewed psychology. Write about what's stuck, walk it through a structured process, and see the thought loosen its grip — usually in under 10 minutes.
No credit card required · Free tier includes the AI co-pilot
Four ways to work with your thinking
Cortex isn't just a blank page. Every feature implements a specific technique from the research literature.
Write freely
Journal with text or voice. Tag your emotions before and after. The AI co-pilot asks follow-up questions — not generic prompts, but questions based on what you actually wrote.
Untangle stuck thoughts
Walk a repeating thought through 7 steps. Name it, examine the evidence, and find a more balanced read. Most people feel the grip loosen in under 10 minutes.
Build your evidence base
Log the things you did that you weren't sure you could do. When doubt shows up next time, Cortex surfaces proof from your own history.
Run experiments on yourself
Pick a technique from the library. Try it for two weeks. Cortex tracks what shifted — emotions, language patterns, recurring themes — so you can keep what works.
The hero feature
Walk a thought through. See it more clearly.
When a thought is stuck on repeat, the Thought Untangler walks you through 7 steps. You examine it from both sides and write a more balanced read. The AI asks questions — you supply the answers.
What was happening?
What went through your mind?
Rate the intensity 0–100
Spot the thinking pattern
Evidence for the thought
Evidence that complicates it
You write the fuller picture
Average intensity drop
Re-rate after the balanced read
Why does this work?
This process is based on cognitive therapy — the most-studied psychotherapy in the literature. A 2023 mega-meta-analysis of 409 trials and 52,000 patients found it consistently outperforms control conditions.
Cuijpers et al., 2023 · Psychological Medicine
Every technique cites its source
Star ratings reflect strength of evidence, not popularity. Pick a protocol, run it for its prescribed window, and see what actually moved.
Three Good Things
★★★Retrain your attention toward what's actually going well
Expressive Writing
★★★Process unresolved experiences through structured writing
WOOP
★★★Connect what you want to what's in the way
Premortem Analysis
★★☆Imagine the failed version to find what you're missing
Affect Labeling
★★★Naming an emotion precisely reduces its intensity
End-of-Day Reflection
★★☆What happened → what did you learn → what will you try differently
More techniques in the library — including implementation intentions, decision journaling, and scheduled worry.
Built to be careful
Safety built in
The AI watches for ruminative spirals and redirects to concrete, constructive framing. If content reaches crisis level, it routes to professional resources — not more journaling.
Socratic partner, not a therapist
The AI asks questions. It doesn't write your thoughts for you. It doesn't diagnose. It helps you see your own thinking more clearly.
Honest measurement
No sycophantic "great job!" messages. Cortex tracks what actually shifted — and tells you when something didn't work, so you can try a different approach.
What Cortex doesn't do
✕ Streak counters that punish you for missing a day
✓ Automaticity curves that show habit forming over time
✕ '21 days to a new habit' countdown bars
✓ Honest data: median 66 days, range 18–254 (Lally 2010)
✕ Generic 'how are you feeling?' prompts
✓ Specific techniques from published research
✕ AI that writes your reflections for you
✓ AI that asks questions so you write them yourself
✕ 'Positive vibes only' affirmations
✓ Balanced thinking: what's the evidence on both sides?
✕ Vision boards without obstacle planning
✓ Mental contrasting: wish + obstacle (WOOP)
Try the Thought Untangler
Pick the thought that's been playing on repeat. Walk it through. See if the number drops. Free — no credit card, no time limit on the free tier.
Get started free