An honest comparison

Kanmail vs Spark

Spark is slick and syncs everywhere by keeping a copy of your mail on its servers. 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

$5–8/mo

free tier · paid billed monthly

  • –Mail copied to 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
–Stored on Spark servers
Third-party processes your mail
✓Never
–Server-side for Smart Inbox & AI
Pricing
✓$49 — one time
Free tier · $5–8/mo 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; paid from ~$4.99–8.25/user/mo. Mail processed & stored server-side for Smart Inbox, sync and AI. Verified June 2026.

Where does your mail actually live?

This is the real difference. To power Smart Inbox, sync and AI, Spark keeps a copy of your email on its servers. 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

Your mail is processed and stored (encrypted) on Readdle’s cloud to enable Smart Inbox, push and AI. Convenient — but it’s no longer only on your device, and true end-to-end encryption isn’t possible.

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 monthly Plus plan. 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 server-side architecture 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, summarize and auto-categorize, powered server-side. 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 →