What Deta Surf is
AlternativeTo files Deta Surf under Note-taking. It is recorded as Free, Open Source — Apache-2.0, from Germany, EU. It ships on Mac, Windows, Linux. The topics its entry raises are offline use, local files and privacy.
That is our reading of the record. For AlternativeTo's own wording, see its page for Deta Surf — the facts above were read on 2026-08-16.
| Price | Free |
|---|---|
| Licence | Open Source — Apache-2.0 |
| Category | Note-taking |
| Origin | Germany, EU |
| Platforms | Mac, Windows, Linux |
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 | Deta Surf |
|---|---|---|
| Price | $1/month, one plan, 7-day trial without a card | Free |
| Licence | Proprietary | Open Source — Apache-2.0 |
| Platforms | macOS, Windows, iOS, Android | Mac, Windows, Linux |
| Category | Note-taking — AI chat into Markdown | Note-taking |
| 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 | Germany, EU |
Where they differ
- Both mention AI. The difference is whose key it runs on: SumizAI never resells inference — you connect one of seven providers (Anthropic, OpenAI, Gemini, Groq, OpenRouter, a local Ollama or your own server) with your own API key and pay that provider directly. Check what Deta Surf does with the model bill before comparing prices.
- Deta Surf is open source (Apache-2.0), and SumizAI is not. If reading the source is what decides it for you, that is a real argument for Deta Surf. 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 Deta Surf 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 Deta Surf. SumizAI runs on macOS, Windows, iOS and Android.
- Both are run from the EU: SumizAI's operator is registered in Poland and the servers are in Germany.
Which one to pick
Reasons to pick Deta Surf
- 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 Deta Surf: AlternativeTo, read 2026-08-16. SumizAI is not affiliated with Deta Surf, and the name is used only to identify the product being compared.
Taken from the AlternativeTo lists: Obsidian.