An honest comparison

Kanmail vs Spark

Spark is slick and syncs everywhere, with Readdle’s servers in the loop. Kanmail keeps your inbox on your machine, and asks for one payment. Here’s the honest side-by-side.

Kanmail

$49

once · on your device

  • ✓Mail never leaves your machine
  • ✓Buy once, no subscription
  • ✓Kanban board on Mac, Win & Linux
VS
SSpark

$99/yr

free tier · Plus billed yearly

  • –Recent mail held on Spark’s servers
  • –Subscription for the good parts
  • –List inbox, no Linux app

Side by side

Spark genuinely wins two rows. We marked them honestly.

Feature
Kanmail
SSpark
Mail stays only on your device
✓Always
–Recent mail kept on Spark servers for 4 hours
Third-party processes your mail
✓Never
–Send later, sharing & AI run off-device
Pricing
✓$49 — one time
Free tier · $99 or $199/yr paid
Inbox layout
✓Kanban board
Smart Inbox (list)
Tracking-pixel blocking
✓On by default
Linux desktop app
✓Yes
–No
Buy once & own it
✓Yes
–No
AI writing assistant
None — by design
✓Compose, summarize
Native mobile apps
–No
✓iOS & Android

Spark (by Readdle): free tier; Plus $99/yr or $10/mo, Pro $199/yr or $20/mo, per user. Spark’s privacy policy says mail is mainly processed on your device, but recent emails are kept on its servers for four hours, send later and shared emails are processed server-side, and AI features use third-party AI providers. Verified September 2026.

Where does your mail actually live?

This is the real difference. Spark keeps recent email on its servers for four hours, and features like send later, sharing and AI process your mail away from your device. Kanmail never does.

Kanmail

Your deviceYour provider

A direct line to Gmail, iCloud, Fastmail — whoever hosts your mail. Nothing in between, nothing to scan, nothing to profile. Tracking pixels blocked by default.

Spark

Your deviceSpark serversProvider

Spark says your mail is mainly processed on your device, but recent emails sit on Readdle’s servers for four hours, send later and shared emails are processed there, and AI requests go to third-party AI providers. Convenient, but your mail is no longer only on your device.

Board, not a list

Spark sorts your list.
Kanmail replaces it.

Spark’s Smart Inbox auto-categorizes a feed for you. Kanmail hands you the controls. Columns you define and drag cards through, so the structure matches your work, not an algorithm’s guess.

Kanmail kanban board

Own it, don’t rent it

One payment, full app.

Spark’s best features sit behind a Plus or Pro subscription. Kanmail is $49 once. Every feature, no tiers, no quotas, and it keeps working whether or not you ever pay again.

Runs where you do

Including Linux.

Same app and license on Mac, Windows and Linux. Spark covers Mac, Windows and mobile but there’s no Linux desktop client.

macOSWindowsLinux

Where Spark wins

That cloud side buys real things. If these matter more than keeping mail on-device, Spark is the better fit.

Real mobile apps

Polished iOS and Android clients with full sync. Kanmail is desktop-only — if your primary inbox is your phone, Spark is the call.

AI writing & Smart Inbox

Compose, rephrase and summarize with AI, plus a Smart Inbox that sorts mail for you. Kanmail is deliberately AI-free and local.

A generous free tier & teams

Real free plan plus shared inboxes and collaboration. Kanmail is a single-user app you buy once.

Keep your inbox yours

$49. Once.

Try Kanmail free for as long as you need. No card, no servers holding your mail. Try free today.

Download Kanmail free →macOS, Windows & Linux

Wondering how paying once works? The email client you buy once →