Inbox Zero vs Shortwave: Open Source or Hosted AI Email?

The real question behind Inbox Zero vs Shortwave AI email is not which one has more features. It is whether you want to own the box the AI runs on. Inbox Zero publishes its code and ships a self-hosting path. Shortwave does not, and does not pretend to — it is a hosted product, and the polish is part of what you are paying for.

That single axis changes almost every other answer. It changes who sees your mail, who fixes it at 2am, what happens to your Gmail API quota, and what you owe if your company grows past five people. Most comparison pages skip it and list features instead.

This page takes the axis seriously. Below: an honest verdict, a dimension-by-dimension table, what self-hosting an AI email assistant actually requires in hours and moving parts, and a licence detail that catches people out. Verify current features and licensing on each project's own site before you commit — both move fast.

The verdict up front#

If you are technical, run a small team, and want the AI touching your mail to run on infrastructure you control, Inbox Zero is a real alternative and the only one of the two that can be. You get the source, a documented self-host path, and the ability to point it at your own LLM provider or a local model.

If you are not going to maintain a server, Shortwave wins and it is not close. It is a finished product with native apps on four platforms, and nobody pages you when the sync breaks. Choosing Inbox Zero to avoid a subscription and then spending six hours a month on it is a bad trade unless the control is the point.

The tie-breaker is not price. It is who is on the hook when something breaks, and whether "the AI never leaves my infrastructure" is a requirement you actually have or a preference you like the sound of.

At a glance: Inbox Zero vs Shortwave#

Where Inbox Zero wins#

Inbox Zero's advantage is structural, not cosmetic. Because the code is public and the self-host path is supported rather than tolerated, you can answer questions about your own mail that a hosted vendor can only answer with a policy document.

The model choice matters more than it looks. The repository supports OpenRouter, Anthropic, OpenAI, Azure OpenAI, Google Gemini, Vertex, Bedrock, Groq, Cerebras and Ollama, plus any OpenAI-compatible endpoint. Pointing an email assistant at a local Ollama model is a genuinely different privacy posture from any hosted product, and it is available to you on day one.

• Data residency you decide. Your database, your region, your backups, your retention.
• Your own Google Cloud project, so the OAuth grant and the Gmail API quota belong to you rather than to a shared vendor app.
• Auditability. If you want to know what the assistant sends to a model, you can read the code that builds the prompt.
• Provider breadth: Gmail and Microsoft/Outlook, where several AI email tools are Gmail-only.
• Cleanup features — bulk unsubscribe, bulk archive, a cold-email blocker and email analytics — that a fast-mail client tends not to prioritise.
• No vendor lock on the model. Swap providers with an environment variable when prices or policies change.

Where Shortwave wins, plainly#

Shortwave is the better product for most people, and that deserves stating without hedging. It is a finished, polished hosted client where Inbox Zero self-hosted is a project you operate.

Its semantic search is the strongest single feature in either product. Asking your inbox a question in plain language and getting the right thread back is the thing people demo to colleagues, and Shortwave has built its identity on it. Inbox Zero's strength is rules and drafting, not retrieval.

It also ships native apps on iOS, Android, Mac and Windows, and the team features — shared threads, assignment, private comments on a thread — are built for people working a shared queue together rather than bolted on.

And there is the thing nobody puts in a feature table: when Gmail changes something and sync breaks, Shortwave's engineers fix it while you are asleep. If you self-host, that is your evening. For most buyers, that alone settles it.

The licence detail most comparisons miss#

"Open source" is doing a lot of work in most write-ups of Inbox Zero, and it is worth being precise, because the precision is the whole reason someone lands on this page.

The repository's LICENSE file is the GNU Affero General Public License v3.0 — and then adds terms from Inbox Zero Inc. on top. Two of those added terms matter. You may not use the software or a derivative for commercial purposes that involve monetising the software itself without written permission. And organisations with five or more employees, contractors or business users must obtain an enterprise licence before using it.

Personal use, education, research and organisations under five business users are exempted. So for a solo operator or a four-person team, the self-host is genuinely free and genuinely yours. For a fifty-person company, "we'll just self-host it" is a licensing conversation, not a deployment decision.

This does not make Inbox Zero a bad choice. It makes it a source-available product with a commercial model attached, which is a normal and defensible thing to be. It is simply not the same as an unrestricted open-source licence, and if your reason for choosing it is that it is open source, you want to know which one you are getting. Read the LICENSE file yourself — it is short.

What self-hosting an AI email assistant actually requires#

This is where most open-source-versus-hosted comparisons go soft. "You can self-host it" is true and nearly useless without the shape of the work. Here is the shape, taken from the project's own setup documentation and environment template.

The happy path is genuinely good by the standards of this category: a CLI wizard and Docker Compose bring up the application with Postgres and Redis. That is the easy half. The hard half is everything that has to exist outside the container.

1. 1

   Stand up the infrastructure

   Docker, a current Node runtime, Postgres and Redis. The project ships a Compose file for local work; for a real deployment you want managed Postgres, backups you have tested, and somewhere for the app to run with a stable public URL.

2. 2

   Create your own Google Cloud project

   You need a Google Cloud project, the Gmail API enabled, an OAuth client ID and secret, and a Pub/Sub topic with a verification token for push notifications. This is the step that takes longest and the one people underestimate.

3. 3

   Get through the OAuth consent screen

   An AI assistant that reads and modifies mail needs sensitive Gmail scopes. In testing mode Google caps how many accounts can use your client. Going beyond your own account means publishing the app and dealing with Google's verification process, which for restricted scopes can include a third-party security assessment. For a single self-hosted user this is usually fine. For a team it is a project.

4. 4

   Add Microsoft credentials if you want Outlook

   A separate client ID, secret and webhook client state, registered in Entra ID. Same idea, different console.

5. 5

   Bring your own AI

   An API key for whichever provider you choose, and the model configuration to go with it. You now pay the model bill directly. That can be cheaper than a subscription or considerably more, depending on how much mail you push through it.

6. 6

   Generate the secrets

   Auth secret, mail encryption secret and salt, internal API key, API key salt. These are not optional and rotating them later is its own small project.

7. 7

   Own it forever

   Upgrades, database migrations, certificate renewals, dependency patches, and the Google API change that breaks sync one morning with no warning. This is the recurring cost and it never goes to zero.

Is the maintenance burden worth it?#

For a single technical user, realistically: an afternoon to stand it up properly, then an hour or two a month, with occasional bad weeks when an upstream API changes. That is a fair trade if control is the point.

For a team, it is different work. You inherit the OAuth verification path, you are the support desk, and you are the one explaining to a colleague why their mail stopped syncing. Unless someone owns it as part of their job, this is where self-hosted AI email quietly dies.

The honest framing: self-hosting buys you control and costs you attention. If nobody on your side has attention to spend, you have not saved money — you have moved a subscription onto someone's evenings.

Pricing model: the shape, not the numbers#

We do not publish competitor prices here, because they change and a stale number is worse than none. What is stable is the shape of each model, and the shape is what you actually plan around.

Inbox Zero has a hosted paid product and a self-hosted path where the software licence is free within the personal and under-five-users exemption. Self-hosting is not free in total, though: you pay for the server, the database and every AI call directly, and the model bill scales with how much mail you process.

Shortwave is a hosted subscription with a time-limited free trial rather than a permanent free plan. Its published tiers changed during 2026 and third-party reviews still describe a free plan that its own pricing page no longer shows — a good reminder to read the vendor page rather than a roundup.

Who each one is genuinely for#

One combination to avoid: choosing the self-hosted option mainly to avoid a subscription, then discovering the AI bill and the maintenance time together exceed what the subscription cost. Self-hosting is a control decision. Treat it as a cost decision and it usually loses.

• Choose Inbox Zero self-hosted if you are technical, run a solo or small operation under the licence threshold, and have a real requirement — regulatory, contractual or personal — that mail content not reach a third-party product.
• Choose Inbox Zero self-hosted if you want to run the assistant against a local model. No hosted competitor offers that, and if it is your requirement, the comparison is already over.
• Choose Inbox Zero hosted if you like its cleanup-and-rules approach — bulk unsubscribe, cold-email blocking, plain-English rules — and want the code to be readable even if you never deploy it.
• Choose Shortwave if search is the job. Asking your inbox questions and getting the right thread is its strongest feature and the reason most of its users stay.
• Choose Shortwave if a team shares a queue and needs assignment, private comments and shared threads inside the mail client rather than a separate tool.
• Choose Shortwave if you have no appetite for maintenance. This is most people and there is nothing wrong with being most people.

A third option, honestly#

We build AI Emaily, so read this section knowing that. It sits in neither column above, and pretending otherwise would waste your time.

AI Emaily is not open source and you cannot self-host it. If source availability is your requirement, Inbox Zero is your answer and we are not. What we optimise for instead is the thing self-hosting is usually a proxy for: control over what the AI is allowed to do with your mail, enforced in the product rather than promised in a policy.

That means explicit autonomy levels — Manual, Copilot and Autopilot — with approval required before anything sends in Copilot, an undo window, and an audit trail of every action the agent took and why. Voice comes from a Personal Context brain you write and per-client profiles you set, not from a model rummaging through your sent folder. We do not train on user mail, and we run zero-retention arrangements with model providers.

We also cover Gmail, Outlook and plain IMAP in one client, with real downloadable desktop apps for macOS and Windows and a native iOS app. On Android we are a PWA, not a native app, and there is no Linux build — if either matters, that is a real mark against us. There is no permanent free tier either: it is a 7-day free trial on Pro and Autopilot, card required, and $0 if you cancel before day seven.

The comparison that matters: if you want the code, take Inbox Zero. If you want a hosted client and Gmail-only search is the job, take Shortwave. If what you actually wanted from self-hosting was a guarantee the AI cannot act without your say-so, that is the thing we built, and you can check it against the trade-offs above.