Shortwave vs Superhuman Mail vs Spark Mail vs SaneBox

Written head to head: Superhuman Mail vs Shortwave, with when to choose each side.

Compared on	Shortwave Free plan · from $18/seat/mo VisitRemove	Superhuman Mail From $25/member/mo VisitRemove	Spark Mail Free plan · from $8.25/user/mo VisitRemove	SaneBox Free trial · from $5.42/mo VisitRemove
What it is	AI email client for Gmail and Google Workspace accounts	AI email app for teams that use Gmail or Outlook	Cross-platform email app with a smart inbox, AI writing and team features	Email filtering service that sorts less important mail into separate folders
Free plan	Basic AI with a limited usage quota; 90 days of standard and AI search history; up to 15 threads per AI search; basic inbox settings; adds a 'Sent with Shortwave' email signature.	No	Unlimited email accounts and core email features; AI assistant limited to 1 month of email history; 5 AI meeting notes (lifetime); 2 free active collaborators; 10 assignments per team; 5 GB team file storage.	No
Cheapest paid plan	$18/seat/mo (Pro)Shortwave pricing	$25/member/mo billed annually (Starter)Superhuman Mail pricing	$8.25/user/mo billed annually (Plus)Spark Mail pricing	$5.42/mo billed annually (Snack)SaneBox pricing
What it covers	Listed as $18 per seat/month on the Individual tab; the pricing page shows no annual billing option.	Mail is also included in the Superhuman suite Business plan ($40 monthly, or $33 per member/month billed annually), which bundles Mail, Grammarly, Docs and Go.	$99 per year when billed annually.	1 email account and 2 SaneBox features; $4.54 per month when paid every two years. Educational, non-profit and government agencies can get 25% off.
Free trial	14-day free trial of paid plans	None stated	7-day free trial of Plus or Pro when subscribing in the app	7-day free trial with all features for up to 4 email accounts
Platforms	Web, macOS, Windows, iOS, Android	macOS, Chrome extension	macOS, Windows, iOS, Android	iOS, Android
Integrations (vendor's figure)	Not stated	Not stated	Not stated	Not stated
Open source	No	No	No	No
Good for	Finding old emails and attachments by asking questions in plain English Sorting a busy Gmail inbox automatically with AI filters Sharing and assigning customer email threads within a small team	Working through a heavy Gmail or Outlook inbox faster Drafting routine replies with AI Sales teams viewing CRM records next to email	Managing several email accounts in one app across computer and phone Drafting and summarising emails with AI Sharing and assigning emails within a small team	Cutting inbox clutter without switching email apps Keeping newsletters out of the main inbox Cleaning up a long-neglected inbox
Watch out for	Sign-in requires Gmail or Google Workspace; Microsoft 365 and Exchange are not supported, and other providers work only through forwarding Free plan limits search history to 90 days and adds a 'Sent with Shortwave' signature Each plan has a daily AI usage quota; higher tiers give more usage	No free plan for Mail; the Superhuman suite's Free and Pro plans do not include Mail Built for Gmail and Outlook users; other email providers are not mentioned on the product page Auto Drafts, Ask AI and CRM integrations require the Business plan	Free plan AI assistant only covers 1 month of email history and includes 5 lifetime meeting notes Free plan allows 2 active collaborators and 10 assignments per team Workflows, Auto-Labels and Auto-Drafts are listed as coming soon on Pro	No free plan; only a 7-day trial Snack covers 1 email account with 2 features; all features require Dinner Relies on folders, which POP email accounts do not support
Made by	Shortwave Communications, Inc.	Superhuman (formerly Grammarly)	Readdle (Spark Mail Limited)	SaneBox, Inc.

Entry prices are the cheapest paid plan, as each vendor publishes it; “What it covers” says what that price is per (a user, a channel, a brand, a number of contacts). The sources are listed on each tool's page.

Every tool in AI email and inbox tools is on its category page, with the written head-to-heads on Compare.