Spark has been a serious contender in the smart-inbox space for years, and Readdle earned that. Smart Inbox, AI summaries, team features, a genuinely good iOS app. Most comparisons that dunk on Spark have not used it seriously. We have.
This one is not a dunk. It is the honest answer to "how is STAMP different from Spark."
What Spark is, in one sentence
Spark is an AI-powered email client that categorizes your inbox into Smart sections, summarizes threads with cloud AI, and layers in team features like shared drafts and comments.
If you manage a shared support inbox with two colleagues and want AI to draft a reply for you, Spark is built for that day.
What STAMP is, in one sentence
STAMP is a triage-first email client that surfaces the threads that need a reply today, classified entirely on-device, with no team layer and no server-side AI.
The difference is not "who has AI." Both do. The difference is what the AI is for and where it runs.
The bets, side by side
| Dimension | Spark | STAMP |
|---|---|---|
| Primary bet | AI summarization makes reading faster | On-device triage makes reading unnecessary for most mail |
| Classification | Cloud AI (OpenAI-backed) | On-device model, nothing leaves the Mac |
| Team features | Shared inbox, comments, delegation | None, built for one person |
| Account types | Gmail, Outlook, iCloud, IMAP | Gmail, Workspace, Outlook, 365, iCloud, Fastmail, Proton Bridge, IMAP/SMTP |
| Pricing | Free tier, Premium subscription | $9/month, $79/year, or $199 lifetime, no free tier |
| Platform | macOS, iOS, Windows, Android | macOS (Apple Silicon) only |
Where Spark wins
Three places Spark is genuinely ahead.
- Team inboxes. If two or three people share support@ or sales@, Spark's delegation and comment threads are a real feature STAMP does not have and is not building.
- Cross-platform reach. Spark runs on every device you own. STAMP is Mac-only, on purpose, but that is a real limitation if you live in Outlook on a Windows work laptop too.
- AI compose maturity. Spark's AI can draft a full reply from a one-line prompt. STAMP does not generate reply text at all right now.
If those three matter to you, Spark is the right choice today.
Where STAMP wins
Three places we are confident we are better.
- Privacy of classification. Spark's summaries and Smart Inbox categorization run through cloud AI. STAMP's triage model runs entirely on your Mac. Nothing about which emails matter, who is urgent, or what a thread says gets sent to a server.
- Built for volume, not just organization. Spark sorts mail into sections. STAMP ranks what needs a reply today across every account you connect, so the morning question is "what are the seven things" not "which section do I check first."
- One clear price, no tiers. $9 monthly, $79 yearly, or $199 once. No free tier that nudges you toward Premium, no per-seat math.
What we won't pretend
Spark's free tier means a lot of people never have to decide anything. STAMP has no free tier, and we think that is the right call for a product this focused, but it does mean the choice to try STAMP is a real commitment from day one. We currently offer 500 founding seats at a locked price during the launch window, which softens that a bit.
A simple test
Look at your last 20 mornings. If most of your email problem is "I have three inboxes and no idea what to answer first," that is a triage problem. If most of your problem is "my team keeps losing track of who replied to what," that is a collaboration problem.
STAMP solves the first. Spark solves both, at the cost of sending your mail through cloud AI to do it.
Who should pick which
Pick Spark if you manage a shared inbox with a team, you need AI to draft full replies, or you use Windows or Android alongside your Mac.
Pick STAMP if you are one person drowning in your own accounts, you want classification that never leaves your device, and you want a Mac-native app that treats triage as the whole job, not one feature among many.
Both products are trying to fix the same broken morning. We just disagree on where the AI should run and who it should be for.
Where to go from here
See what shipped recently on the changelog, or check pricing and the founding window if you are ready to try STAMP.
See for yourself. hello@stamp.email