Email tool comparison
ForthWrite vs Microsoft Copilot
Native to Microsoft 365. Locked to one model. Locked to one ecosystem.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.
Microsoft Copilot
Microsoft's AI assistant for Outlook, Word, Teams, and the rest of M365. Deep ecosystem integration; single-model, single-vendor.
Where they win
- Native Microsoft 365 integration across Outlook, Word, Excel, Teams, SharePoint
- Strong calendar + meeting context inside the Microsoft graph
- Enterprise-grade compliance, data residency, and admin controls
- Familiar surface for orgs already standardized on Microsoft 365
What they don't do (or charge extra for)
- No BYOK and no model choice — you get whatever Microsoft ships
- Personal Outlook requires a paid M365 Personal/Family subscription before Copilot Pro can be added
- No closed-loop edit supervision or measurable voice-improvement curve published
- Locked to the Microsoft ecosystem — same tool can't help you in Gmail
- Higher per-seat price than the depth-on-voice alternatives
Pricing: Copilot Pro $20/mo (consumer, requires paid M365 Personal/Family first). Microsoft 365 Copilot $30/seat/mo (commercial, annual commit).
Best for: Microsoft 365 shops that want a single-vendor AI layer across the whole Office suite and accept locked-in model choice.
Head-to-head
The product-behavior comparison, not the marketing-page comparison.
ForthWrite works in Outlook today — voice-matched, model-flexible, free to start.
Copilot is built for Microsoft-standardized orgs that want one AI layer everywhere — Outlook, Word, Excel, Teams. If that's you and your IT department has already paid for it, great. The question this page answers is: what if you want AI specifically for email, and you'd like it to actually sound like you?
ForthWrite runs inside Outlook Web (personal outlook.com, work outlook.office.com, and Microsoft 365 outlook.office365.com) with no IT ticket and no Copilot Pro add-on. Free tier includes voice matching — drafts get more like you after every send, because the system compares each AI draft to what you actually sent and uses the gap as a training signal. Copilot doesn't publish a comparable feedback loop.
On model choice: ForthWrite Standard and Pro ship with 9-provider BYOK. Same draft, different model — route a sensitive client reply through Claude, a quick acknowledgment through a fast cheap model, a research-heavy thread through GPT. Copilot gives you whatever Microsoft ships, take it or leave it.
On price: ForthWrite Standard is $18/mo (BYOK saves ~17%); Pro is $36/mo. Copilot Pro for personal use is $20/mo on top of a paid Microsoft 365 Personal subscription. The math is closer than it looks once you account for the M365 prerequisite.
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 Microsoft Copilot draft and decide for yourself.