What Reply4 is
AlternativeTo files Reply4 under AI Writing. It is recorded as Paid, Proprietary. It ships on Online. The topics its entry raises are collaboration.
That is our reading of the record. For AlternativeTo's own wording, see its page for Reply4 — the facts above were read on 2026-08-16.
| Price | Paid |
|---|---|
| Licence | Proprietary |
| Category | AI Writing |
| Origin | AlternativeTo does not say |
| Platforms | Online |
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 | Reply4 |
|---|---|---|
| Price | $1/month, one plan, 7-day trial without a card | Paid |
| Licence | Proprietary | Proprietary |
| Platforms | macOS, Windows, iOS, Android | Online |
| Category | Note-taking — AI chat into Markdown | AI Writing |
| Where notes live | Standard .md files in a folder you choose | AlternativeTo does not say |
| AI model | Seven providers, always on your own API key | Its description mentions AI |
| Origin | Poland, EU | AlternativeTo does not say |
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 Reply4 does with the model bill before comparing prices.
- Reply4 is paid software. Compare the two numbers directly: SumizAI is one dollar a month, one plan, and your AI provider bills you separately for the model you chose.
- AlternativeTo's description of Reply4 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. - Reply4 is described as something more than one person uses at once. SumizAI is not: there are no shared vaults, no comments, no permissions and no sync between devices. If the work is a team's, that is a reason to pick Reply4 over SumizAI.
- Reply4 runs in the browser. SumizAI is a desktop and mobile application, and on the desktop the vault is a folder on your own disk rather than a document in someone's cloud.
Which one to pick
Reasons to pick Reply4
- more than one person works in the same notes
- you need it to run in a browser
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 Reply4: AlternativeTo, read 2026-08-16. SumizAI is not affiliated with Reply4, and the name is used only to identify the product being compared.
Taken from the AlternativeTo lists: ChatGPT.