Where they genuinely overlap
Both let you upload PDFs, slides, documents and recordings, and generate study material from them. Both cover flashcards, quizzes, summaries, study guides and essay support. If your requirement is "turn this pile of course material into something I can revise from", both products do that, and you would be reasonably served by either.
Atlas has a free tier, which is a real advantage and the reason most people try it first. It is available as native iOS and Android apps as well as on the web. It is a mature, well-built product with a lot of users. We are not going to pretend otherwise.
The difference that actually matters
The question that separates AI study tools is not which features are on the box. It is: what does it do when your material doesn't contain the answer? There are only two possible behaviours. It can tell you. Or it can answer anyway, from what the underlying model already believed, in exactly the same confident voice it uses when it is reading your slides.
Thaxas is engineered around the first behaviour, at three independent layers: a similarity floor that aborts before the model is called, a required refusal sentinel in the prompt, and a visible badge in the interface when an answer ran outside your material. Answers cite the page they came from. When the page doesn't exist, you are told, rather than being handed a plausible paragraph the night before an exam.
We are not claiming Atlas hallucinates. We are claiming that if grounding is the property you care about, you should test it rather than take anyone's word — including ours. Which is the point of the next section.
How to test either of them in five minutes
- 1
Upload one lecture — not your whole course
A single deck or chapter, so you know exactly what is and isn't in the material.
- 2
Ask something the material definitely covers
Check the answer is right, and check that the citation points at the page you expect. Any decent tool passes this.
- 3
Now ask something adjacent that it definitely does not cover
A topic from next term. A concept the lecturer explicitly skipped. This is the whole test, and most tools fail it.
- 4
Read what comes back, very carefully
Did it say the material doesn't cover this? Or did it produce a fluent, correct-sounding answer with no source? If it did the second thing, you now have no way to tell — for any future answer — which mode you were in.
Side by side
| Thaxas | Atlas | |
|---|---|---|
| Free tier | No — $12/mo, or $8/mo billed yearly | Yes, with limits; paid tiers above it |
| Mobile apps | Web, works on mobile browsers | Native iOS and Android |
| Answers cite the source page | Yes, on every claim | Check for yourself with the test above |
| Explicit 'not in your material' refusal | Yes — enforced at three layers | Check for yourself with the test above |
| Spaced repetition | Real FSRS-4.5, tested against reference values | Flashcard review; check the scheduling model |
| Shared study material | Shared folders; progress stays private | Sharing features available |
_Written in July 2026 from publicly available information. These products ship constantly, so check their site before you decide — and tell us if we've got something wrong._