What cs.AI is
AlternativeTo files cs.AI under AI Chatbot, Large Language Model (LLM). It is recorded as Free, Open Source — MIT, from United States. It ships on Mac. The topics its entry raises are offline use, chat, large language models and search.
That is our reading of the record. For AlternativeTo's own wording, see its page for cs.AI — the facts above were read on 2026-08-16.
| Price | Free |
|---|---|
| Licence | Open Source — MIT |
| Category | AI Chatbot, Large Language Model (LLM) |
| Origin | United States |
| Platforms | Mac |
What SumizAI is
A note-taking application built around a conversation with an AI model. You ask a question, the answer streams back, and the answers worth keeping become Markdown notes — filed into a vault that is a folder on your own disk.
A vault is a directory holding base.md, a generated table of contents up to six levels deep, and a notes/ folder with one .md file per note. Before a note is written it is checked against the ones already there, so the fourth note about the same idea gets merged instead of added. Links between notes are ordinary Markdown links to files that exist.
The model is never ours: you bring your own API key to one of seven providers — Anthropic, OpenAI, Gemini, Groq, OpenRouter, a local Ollama or your own server — and pay that provider directly. A question sends the table of contents plus at most five relevant notes within a 24,000-character budget, and the app shows you which five it used.
Side by side
| Side by side | SumizAI | cs.AI |
|---|---|---|
| Price | $1/month, one plan, 7-day trial without a card | Free |
| Licence | Proprietary | Open Source — MIT |
| Platforms | macOS, Windows, iOS, Android | Mac |
| Category | Note-taking — AI chat into Markdown | AI Chatbot, Large Language Model (LLM) |
| Where notes live | Standard .md files in a folder you choose | Its description mentions local or offline files |
| AI model | Seven providers, always on your own API key | Its description mentions AI |
| Origin | Poland, EU | United States |
Where they differ
- cs.AI is a place to have the conversation. SumizAI is not a chatbot — the conversation is the input, not the product. What comes out of it is a
.mdfile with a title, a place inbase.mdand a duplicate check against the notes already in the vault. If you only want to talk to a model, you do not need SumizAI. - cs.AI is open source (MIT), and SumizAI is not. If reading the source is what decides it for you, that is a real argument for cs.AI. The guarantee SumizAI offers instead is structural rather than legal: the notes are Markdown files in a folder you chose, so they open in any editor whether or not the application is running.
- AlternativeTo's description of cs.AI does not mention Markdown, so check what format your notes end up in before you fill it up. SumizAI writes standard
.mdfiles to a folder you picked, and an unpaid account can still export all of them. - AlternativeTo lists no mobile version of cs.AI. SumizAI runs on macOS, Windows, iOS and Android.
- Both search. SumizAI's search reads the whole note — title, summary, body and the original question and answer — rather than titles alone.
Which one to pick
Reasons to pick cs.AI
- the source is open and you want to read it
- it costs nothing
Reasons to pick SumizAI
- the notes you want already exist inside conversations with an AI model
- you want the filing — title, chapter, duplicate check — to happen without you
- you want the result as plain
.mdfiles in a folder you picked - you would rather pay your AI provider directly than have a note app resell the model
Facts about cs.AI: AlternativeTo, read 2026-08-16. SumizAI is not affiliated with cs.AI, and the name is used only to identify the product being compared.
Taken from the AlternativeTo lists: ChatGPT.