Compare
LetterLeaf vs Superhuman
One is the fastest email client you can buy. The other is an inbox built for triage across every account you own. Here is where they differ.
side by side
Where they differ
LetterLeaf
Superhuman
What it is
An inbox built for triage, with categories written back to Gmail and Outlook
A faster email client that replaces Gmail or Outlook on Mac, Windows, web, iOS and Android
Works with
Gmail, Outlook, Microsoft 365 shared mailboxes, any IMAP
Gmail and Outlook
Sorting
Categories from a template for your business, editable
Split Inbox streams you configure; Auto Labels on Business
Needs-a-reply and requires-attention views
✓ Smart Views across every inbox
Split Inbox, set up by you
Sentiment on every email
✓ all plans
—
Focus Mode: one email at a time to inbox zero
✓
Keyboard-driven triage, 100+ shortcuts
Drafts in your voice
✓ learned from your sent mail
✓ Instant Reply; Auto Drafts on Business
Chat with an agent about the draft
✓ Email Agent
Ask AI on Business
Drafts grounded in your own documents
✓ Smart Docs, Professional and up
—
Thread summaries
✓ saved with the email
✓ Auto Summarize
Workflow builder and SLA escalation
✓ Business
—
Shared team inboxes with roles
✓ Professional and up
Shared conversations and read statuses, no shared inbox
Calendar inside the mail app
—
✓
Raw speed
Normal web app
Its whole reason to exist
Where AI processing runs
EU, Microsoft Azure EU data zone
Not stated on their site
Price per user, monthly billing
$29 · $49 · $69
$30 Starter · $40 Business
Price per user, annual billing
$25 · $40 · $55
$25 Starter · $33 Business
Free trial
7 days, 100 AI-powered emails, no card
No free plan
Superhuman details taken from superhuman.com on 3 October 2026. If something has changed, tell us and we will fix it.
the short version
Which one is for you
Pick Superhuman if
You want the fastest client there is
You live by keyboard shortcuts and measure email in milliseconds
One Gmail or Outlook account is your whole inbox
You want calendar and mail in one window
Pick LetterLeaf if
You want an inbox built for triage
Smart Views, sentiment and Focus Mode: work through what needs you, then stop
You use Fastmail, Zoho, Proton via bridge, or mail on your own domain
A shared support@ or sales@ inbox is answered by a small team
Replies must quote your real prices, policies and dates
You care where your email is processed
an inbox built for triage
Smart Views, sentiment, Focus Mode
Superhuman makes you faster at working through everything. LetterLeaf shows you less: every message gets a category from your business template, a sentiment face, and a place in Needs a reply or Requires attention. Focus Mode then walks you through that queue one email at a time.
replies
In your voice, with your facts, with an agent beside the draft
Both draft in your tone. Superhuman’s Auto Drafts and Ask AI sit on the Business plan. LetterLeaf grounds every draft in Smart Docs, the files, snippets and website pages you give it, and the Email Agent rewrites on request: shorter, more formal, a polite decline.
categories
Categories that match your business
Pick SaaS, e-commerce, law firm, agency or a dozen others and LetterLeaf starts with categories that fit, then lets you rename, add or remove them. Superhuman’s Split Inbox is powerful but you build each stream yourself.
to be fair
What LetterLeaf does not do
LetterLeaf is not a speed-first client: there is no 100-shortcut keyboard layer and no built-in calendar. If raw speed in one Gmail account is the goal, Superhuman is the better fit and we would rather say so than have you find out on day three.