An open-source AI email assistant, or a unified inbox built for teams.
Inbox Zero is a well-regarded open-source AI email assistant for Gmail and Outlook with Slack and Telegram integrations and a 9k+ star GitHub repo. this+that is also an AI-native inbox, but the bet is broader: a unified surface across email, chat, and calendar; a real task model on top of incoming messages; a plain-language workflow builder; and a team-shared knowledge brain. Same conviction that AI belongs inside the inbox. Different bets on how open the stack should be, and how much further the inbox should reach.
Open source for your email, or wider scope built for teams
<p>Both products belong to Wave 2 of AI for work, the fit-for-purpose tier where the AI lives inside the work surface, not in a separate chat window. (More in our <a href='/blog/ai-second-wave'>essay on AI's second wave</a>.) Both rebuild the inbox from scratch around AI. Both ingest email and message content directly and act on it. The differences are about openness and breadth.</p><p>Inbox Zero is open source under an AGPL licence with thousands of GitHub stars. You can run it yourself for free, audit the code, and self-host the whole stack. That is a real and respectable choice, particularly for teams who treat self-host and audit as non-negotiable. The hosted version starts at $18 per user per month with a clear free trial and self-host fallback. The product focuses on email triage: AI drafting in your voice, automatic sorting, cold-email blocking, bulk unsubscribe, email analytics, and a knowledge base.</p><p>this+that is not open source. We rebuild the inbox as a unified surface where email is one input among many: Gmail, Outlook, Slack, Microsoft Teams, Google Chat, Telegram today, with Instagram, Facebook Messenger, and WhatsApp coming soon. Calendar events and attachments flow through the same surface. On top of that, we run two layers that Inbox Zero does not have today: a real task model (DoBox) that extracts assignable tasks out of every message with provenance back to the source, and a plain-language workflow builder with 32 action types, IF/ELSE branching, loops, and sub-agents. And the brain, a writable team knowledge layer that agents and humans share.</p><p>If the highest-value problem is a clean, auditable open-source email triage tool that you control end to end, Inbox Zero is one of the strongest options on the market. If the problem is the work that arrives across every channel a team uses, and you want one place to read it, extract tasks from it, automate it, and ground it in a shared team knowledge layer, that is what we built this+that for.</p>
Feature by feature
How the two products compare across the things that matter most.
| Topic | Inbox Zero | this+that |
|---|---|---|
| Category | Wave 2. Open-source AI-native email assistant focused on triage and drafting. | Wave 2. AI-native unified inbox across email, chat, calendar, and DMs, with tasks and workflows on top. |
| Licence | Open source (AGPL). 9k+ GitHub stars. Self-host free. | Proprietary, hosted by us. Free during beta. |
| Email providers | Gmail and Outlook. | Gmail and Outlook. |
| Messaging channels | Slack and Telegram today. Microsoft Teams coming soon. | Slack, Microsoft Teams, Google Chat, and Telegram today. Instagram, Facebook Messenger, and WhatsApp coming soon. |
| Task extraction | Email triage with smart labels, prioritization, and a reply queue. No persistent assignable task model. | DoBox scans every message across every channel for requests, commitments, deadlines, and follow-ups, surfaced as assignable tasks for the team with provenance back to the source message. |
| Workflow automation | Rule-driven assistant behaviour configurable in natural language. Drafting, sorting, blocking, unsubscribing, pre-meeting briefings. | Plain-language workflow builder. 32 action types, IF/ELSE branching, loops, sub-agents. Triggered by messages, schedules, or manual runs. |
| Team knowledge | A knowledge base attached to the user for grounding AI replies (Plus tier and above). | The brain. A writable team knowledge layer with personal and team spaces. Agents read and write. Pages can be published outward as public artifacts that visitors can query, with live calendar booking on the same artifact. |
| Voice and tone | Drafts replies in your voice based on prior emails. | Drafts in your voice across every channel based on your prior messages, with per-team or per-channel overrides. |
| MCP / external agents | Not a first-class feature today. | Open MCP first-class. We host an MCP server you can connect external agents to; we also call external MCP servers from workflows. |
| Calendar | Calendar-aware drafts and pre-meeting briefings. | Read and write. Workflows can RSVP, create, and reschedule. Public artifacts can show live availability and let visitors book a demo against your real calendar. |
| Team features | Team-wide analytics on the Professional tier; SSO and SCIM on Enterprise. | Task assignment, shared task views, team-request grounding (your agent searches a teammate's brain to draft a suggested reply), and team-owned workflows. |
| Privacy stance | Self-host option means data stays on Customer infrastructure. Hosted version processes through their stack. | No training on customer data, including anonymised. Contractual commitment in our DPA. AWS-owned encryption keys; no this+that employee can decrypt content. |
| Pricing | Self-hosted free. Hosted: Starter $18, Plus $28, Professional $42 per user per month (20% off annual). Enterprise custom. | Free during beta. |
- Open source is the real differentiator. AGPL licence, 9k+ GitHub stars, audit anything, fork anything, self-host for free if you have the operations capacity.
- A clean, focused email-AI experience. Sorting, drafting, blocking cold email, bulk unsubscribe, calendar-aware briefings. The product does what it says.
- Transparent pricing. $18 to $42 per user per month with a clear free trial, plus the self-host option as a real free path for teams who want it.
- Multi-channel support beyond email. Slack and Telegram are already in; Microsoft Teams is on the roadmap. Most email-AI products are still Gmail-only.
- A reasonable choice for teams whose biggest problem is email triage and who treat self-hosting and code-level auditability as serious requirements.
- A unified inbox in the literal sense. You read email, Slack, Teams, Google Chat, and Telegram messages in the same place today, with Instagram, FB Messenger, and WhatsApp coming soon, instead of jumping between tabs.
- Microsoft Teams is live, not coming soon. If half your team is on Outlook and Teams, you can adopt now.
- Real workflows. 32 action types, IF/ELSE, loops, sub-agents. The kind of automation depth you would otherwise wire up in Zapier or Make, with an agent doing the decisions, not just labels and rules.
- A real task model. DoBox extracts assignable tasks from every message with one-click provenance back to the source thread. Email triage helps you process the inbox; DoBox helps you finish the work.
- The brain: a writable team knowledge layer that agents and humans share. Pages can be published outward as public artifacts that answer customer questions and let visitors book against your real calendar.
- Open MCP first-class. Connect external agents (Claude, Codex, others) to your this+that data, and call external MCP servers from workflows.
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