this+that vs Inbox Zero
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, reachable from Slack, Teams or Telegram, with a repo approaching 12,000 stars. this+that’s 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 license with nearly 12,000 GitHub stars. You can audit the code and self-host the whole stack, which is a respectable choice for teams who treat that as non-negotiable. Read the license before you plan on it being free, though: the additional terms say an organization with five or more employees, contractors or users running it for business purposes must obtain an enterprise license, so free self-hosting covers personal use and teams under five. The hosted version starts at $20 per user per month billed monthly, or $16 billed annually, with a clear free trial. 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’s 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, WhatsApp Business today, with Instagram and Facebook Messenger coming soon. Calendar events and attachments flow through the same surface. On top of that, we run two layers that Inbox Zero doesn’t 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 a broad action set, conditional logic, 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’s 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. |
| License | Open source (AGPL with additional terms). Nearly 12,000 GitHub stars. Self-hosting is free for personal use and for organizations with fewer than five business users; at five or more, the license requires an enterprise license from Inbox Zero Inc. | Proprietary, hosted by us. Free for 30 days, including 3,000 credits. Then $35 per user per month, or $29 billed annually, with 3,000 credits a month per person. |
| Email providers | Gmail and Outlook. | Gmail and Outlook. |
| Messaging channels | None that it reads. Slack, Microsoft Teams and Telegram are places to chat with the assistant and receive its drafts and updates, per their docs. Email is the only thing it acts on. | Slack, Microsoft Teams, Google Chat, and WhatsApp Business today. Instagram and Facebook Messenger 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 behavior configurable in natural language. Drafting, sorting, blocking, unsubscribing, pre-meeting briefings. | Plain-language workflow builder. A broad action set, conditional logic, 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, an FAQ or pricing page that answers common visitor questions, with a live booking widget on the same page that books against your real calendar. |
| 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. Message content encrypted under dedicated KMS keys; employees read it only with your permission or for emergency support, and that access is temporary and logged. |
| Pricing | Self-hosted free under five business users; an enterprise license is required at five or more. Hosted: Starter $20, Plus $35, Professional $50 per user per month billed monthly; $18, $28, and $42 billed annually. Enterprise custom. | Free for 30 days, including 3,000 credits. Then $35 per user per month, or $29 billed annually, with 3,000 credits a month per person. |
- Open source is the real differentiator. AGPL license, nearly 12,000 GitHub stars, audit anything, fork anything, self-host it if you’ve the operations capacity. Free self-hosting stops at five business users under the license, so budget for an enterprise license above that.
- A clean, focused email-AI experience. Sorting, drafting, blocking cold email, bulk unsubscribe, calendar-aware briefings. The product does what it says.
- Transparent pricing. $20 to $50 per user per month billed monthly, or $18 to $42 annually, with a clear free trial.
- Reachable from where you already are. Slack, Microsoft Teams and Telegram let you chat with the assistant and receive its rules, drafts and updates, per their docs, which is a convenience layer rather than extra channels it reads. Email is the only thing it works on, and it covers Outlook as well as Gmail, which not every rival does.
- 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 WhatsApp Business messages in the same place today, with Instagram and FB Messenger coming soon, instead of jumping between tabs.
- Teams and Slack are channels we read, not just places to reach an assistant. If half your team agrees things in Teams, those requests become tracked work here and stay invisible there.
- Real workflows. A broad action set, conditional logic, 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 is a writable team knowledge layer that agents and humans share. Pages can be published outward as public artifacts that answer common customer questions, with a live booking widget that lets 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.
What is Inbox Zero?
Inbox Zero is an open-source AI email assistant for Gmail and Outlook, with nearly 12,000 GitHub stars and an AGPL-plus-riders license. It handles email triage: AI drafting in your voice, automatic sorting, cold-email blocking, bulk unsubscribe, email analytics, and a knowledge base. You can reach the assistant from Slack, Microsoft Teams or Telegram, though per their docs those are places to chat with it and receive drafts rather than channels it reads. Because the whole stack is open source you can audit the code and run it on your own infrastructure, which for some teams is the entire reason to choose it.
How much does Inbox Zero cost?
Self-hosting is free for personal use and for organizations with fewer than five business users. At five or more the license's additional terms require an enterprise license from Inbox Zero Inc., so most companies evaluating it should read the hosted prices as the real prices. The hosted product is $20 per user per month on Starter, $35 on Plus and $50 on Professional, or $18, $28 and $42 respectively when billed annually. Enterprise is custom. this+that’s free for 30 days. Worth weighing the real cost of self-hosting rather than the sticker price: running it yourself means someone owns deployment, upgrades and uptime, which is cheap if you already have that capacity and expensive if you don’t.
Who should choose Inbox Zero?
If code-level auditability and self-hosting are non-negotiable, Inbox Zero is one of the strongest options available and we would point you there without hesitation. We aren’t open source and can’t be self-hosted. It is also a clean, focused email product: the triage, sorting and unsubscribe features do what they say without much ceremony. Teams whose central problem is email volume, and who have the operational capacity to host, should look at it first.
Looking for an Inbox Zero alternative?
The usual reason is scope. Inbox Zero is built around triaging email well. If the problem is that work arrives across email and chat and then has to become tracked, assigned and acted on, that’s a different job. this+that reads Gmail, Outlook, Slack, Teams, Google Chat and WhatsApp Business as one stream, extracts tasks with a link back to the message they came from, and runs plain-language workflows with conditional logic and sub-agents on top.
See what's waiting in your inbox
Connect your inbox and this+that starts reading it. The tasks, follow-ups, and open commitments buried in your messages become tracked work, and what your team knows starts collecting in one place.
Free for 30 days · Then $35 per user per month · $29 billed annually