Pick the wrong AI email tool and every minute you save comes straight back. None of these four is good at everything. There is only one way to split them: first ask yourself whether you will switch clients, then ask which mailbox you use and whether you will pay for speed and searching old mail. Only once you have sorted the audiences in this order do the prices and features below make sense.
First, work out which group you belong to
If you do not want to switch clients, stay in Gmail and add AI there. If you are willing to switch, split further by mailbox: if you only use Gmail, first check whether you can dig up old mail; if you mix Gmail and Outlook and handle hundreds of emails a day, prioritise speed; if you mix several mailboxes and have a limited budget, first check whether the free tier is enough. Once this layer is clear, you can compare prices and features without being led astray by a single selling point.
The four tools side by side
| Tool | Monthly price (US price, check the official website) | Best for | Not for |
|---|---|---|---|
| Superhuman | Starter $30, $25 with annual billing; Business $40, $33 with annual billing; no free tier | People who handle hundreds of emails a day and make their living on reply speed | People on a tight budget; people who use mailboxes such as iCloud, QQ, or 163 |
| Shortwave | Free tier $0; Pro $18, Business $30, Premier $45, Max $120 | People who only use Gmail and often dig through emails from years ago for answers | People who do not use Gmail; people who buy only individual Pro but want team features |
| Spark | Free tier $0; Plus $10, $99 per year with annual billing; Pro $20, $199 per year with annual billing | People who mix several mailboxes, have a limited budget, and want to try it free first | People who do not want to store their mailbox credentials on a third-party server; people who do not want to switch clients |
| Gmail Gemini | Smart Compose and Smart Reply free; full features need a Google AI plan, Plus from $4.99 | People who do not want to switch clients and are already in the Google ecosystem | People who do not use Gmail; people who only want free, full AI |
The verdict by audience: who picks which, and who should stay away?
If you only use Gmail and often search old mail, pick Shortwave: AI search only looks at mail from the last 90 days, from Pro it covers 3 years and Business 5 years — but it only supports Gmail, so if you do not use Gmail, do not consider it. If you mix Gmail and Outlook, have enough budget, and want the fastest option, pick Superhuman: its selling points are keyboard operation, Split Inbox, and automatic summaries; it starts at $30 a month, and the mailbox itself has to be paid for separately, so it is not worth it for low volumes. If you mix several mailboxes and want to try it free first, pick Spark: the free tier includes Smart Inbox and unlimited mailbox accounts, while the full AI assistant needs Plus, from $10 a month. If you do not want to switch clients, stay in Gmail and use Gemini: full drafting, long-thread summaries, and AI search need a paid plan, and features roll out by region, language, and account — go by what your own account actually shows.
