Email tool comparison
ForthWrite vs Superhuman
Elite email client. Drafts are a feature, not the product.Here's where each tool wins, and where the depth-on-voice differentiator actually matters.
ForthWrite
A writing platform for people who care how their email reads. Voice matching on every tier; closed-loop edit supervision on Standard+; auto-draft, batch, and Prompt Lab on Pro. 9-provider BYOK.
Where we win
- Closed-loop edit supervision (compare drafts to what you sent)
- Measurable improvement curve on the dashboard
- 9-provider BYOK on Standard and Pro
- Standalone web compose surface in the browser
- Free tier includes voice matching (not just basic drafting)
Pricing: Standard $18/mo, Pro $36/mo. BYOK saves ~17%.
Best for: Professionals who want their email to keep sounding like them - and want to see the improvement curve.
Superhuman
Premium email client with split-inbox, snippets, scheduled send, and AI Instant Reply layered on top.
Where they win
- Best-in-class email client UX (keyboard-first, fast, polished)
- Mature shortcuts, snippets, scheduled send, split inbox
- Drafts in your "voice and tone" using inbox, calendar, web, uploaded knowledge
- Strong brand and existing premium customer base
What they don't do (or charge extra for)
- You have to switch email clients - Superhuman is the inbox, not a layer
- Single-provider AI; no BYOK or model choice
- No closed-loop edit supervision or measurable improvement curve
- Premium price (~$30/mo) without the multi-provider or depth-instrumentation differentiators
Pricing: ~$30/mo individual; Teams pricing varies (as of 2026).
Best for: Users who want a premium email *client* with AI as one of many features, and are willing to switch away from Gmail's UI to get the rest of the package.
Head-to-head
The product-behavior comparison, not the marketing-page comparison.
If you want the polished-client experience, Superhuman wins this row.
ForthWrite doesn't ask you to switch clients - and goes deeper on voice fidelity.
Superhuman is an email client. ForthWrite is a voice system that lives inside the client you already use. If you love Gmail's interface and don't want to learn a new tool, that's the first difference - Superhuman makes you switch; ForthWrite doesn't.
On voice depth: Superhuman writes drafts in your "voice and tone" using inbox + calendar + web + uploaded knowledge. That's a one-shot synthesis. ForthWrite runs a closed loop: every AI draft is compared to what you actually sent, the gap becomes a training signal, the voice profile regenerates every ~50 captured sends, and the dashboard shows the improvement curve. One is a claim; the other is a measurement.
On model choice: ForthWrite Standard and Pro ship with 9-provider BYOK so you can route different emails to different models. Superhuman gives you their model.
Coexistence note: ForthWrite works inside Superhuman's Gmail-based client too if you've already paid for Superhuman. You don't have to pick - the extension layers on either way.
See the improvement curve for yourself
Free tier includes voice matching. No credit card, no API key. Compare your first ForthWrite draft to your first Superhuman draft and decide for yourself.