SumizAI vs HackFlowy

What HackFlowy is

What HackFlowy was

HackFlowy was an open-source clone of Workflowy — the nested-list note app known for its minimalist approach to infinitely indentable bullet points. It was built on Backbone.js for the frontend and Socket.io for real-time sync, designed for self-hosting rather than relying on someone else's cloud service. Several independent forks of the same codebase circulate on GitHub, typical of a small student or hobby project from that era.

Project status

HackFlowy is no longer maintained. The last activity across its repositories dates back many years, with no commits, releases, or replies to issues — the common fate of a small open-source project that served its purpose as a technical exercise without building a community large enough to sustain long-term upkeep. The code is still publicly available and could theoretically be self-hosted, but it requires manual work on dependencies that have since gone stale.

Architecture and deployment

A Node.js backend with Socket.io handled real-time sync between open tabs or devices, while the frontend used Backbone.js and the Foundation framework for styling. Deployment instructions involved editing config files, running `npm install`, and starting `node server.js`, with an option to deploy on Heroku for anyone who didn't want to manage their own server.

Key features (as they were)

Unlimited-depth nested bullet points, keyboard navigation for quickly moving through and indenting list items, and real-time sync between clients connected via Socket.io.

Who it made sense for

People wanting to self-host a simple Workflowy clone instead of paying for a commercial service, and developers learning Backbone.js and Socket.io through a practical example — HackFlowy also doubled as a learning resource, evidenced by the many forks with small tweaks. Nobody on that list was thinking about ai notes back then — the whole concept of an ai notes entry from a conversation with an assistant didn't exist yet when the project was built.

Limitations and what to watch for

No security updates in years makes running HackFlowy on a publicly reachable server risky — Node.js dependencies from that period may carry known vulnerabilities. Anyone considering a self-hosted deployment should treat it as a learning exercise or local experiment rather than a production tool for storing important notes.

AI notes and the archive that never existed

HackFlowy never integrated with AI models — it's a relic from before conversational assistants existed. Anyone looking today for a place to keep ai notes from a conversation with a language model won't find any import mechanism or formatted paste support here; the only option would be manually retyping content into nested bullets, losing the original response structure in the process.

What's worth checking before choosing

Before setting up a self-hosted instance, it's worth checking which of the several GitHub forks carries the most recent (if still old) dependencies, and weighing whether an actively maintained, modern open-source nested-list tool would be a safer choice today.

Bottom line

HackFlowy is a frozen-in-time, abandoned Workflowy clone — interesting as a historical artifact and learning resource, but not a fit for daily note-taking in 2026.

Comparison with SumizAI

HackFlowy and SumizAI share little beyond the broad category of "notes." HackFlowy is an abandoned, self-hosted nested-list clone with no AI layer at all. SumizAI is an actively developed notebook where these notes come directly out of a conversation with a language model — a question, an answer, then a Markdown file landing in a vault the user owns, with seven supported AI providers on the user's own API key. Anyone looking for a living, supported tool to build an archive of these notes from AI conversations will find in SumizAI something HackFlowy never offered, even in its best days.

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.

Every answer kept this way becomes one of these ai notes, ready to search again months later without hunting back through old chats.

Side by side

Where they differ

• AlternativeTo flags HackFlowy as no longer developed. Whatever you put into it, you will eventually have to get back out — which is an argument for keeping notes in a format that outlives the application, and the reason SumizAI writes plain .md files into a folder you already own.
• AlternativeTo's description of HackFlowy does not mention an AI model. That is the whole starting point in SumizAI: you have a conversation with a model on your own API key, and the answers worth keeping become notes without you filing them.
• HackFlowy is open source, and SumizAI is not. If reading the source is what decides it for you, that is a real argument for HackFlowy. 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 HackFlowy does not mention Markdown, so check what format your notes end up in before you fill it up. SumizAI writes standard .md files to a folder you picked, and an unpaid account can still export all of them.
• HackFlowy can be self-hosted. SumizAI has nothing to host on the desktop — the vault is a folder on your machine — and if you want the model on your own hardware too, a local Ollama is one of the seven providers it speaks to.
• AlternativeTo lists no mobile version of HackFlowy. SumizAI runs on macOS, Windows, iOS and Android.

Which one to pick