Letterbook vs Plain

See how their public offers line up before you choose your own position. Prices stay in the currency, billing schedule, and charged unit each vendor publishes.

Letterbook

See full pricing history

USD · US · source: www.letterbook.ai

Plan	Pricing	Charged by	Offer type
Starter — default	USD 50 monthly · USD 50 / month with annual commitment $50 per month	Flat · per month	Standalone · Fixed
Growth — default Highlighted	USD 200 monthly · USD 200 / month with annual commitment $200 per month	Flat · per month	Standalone · Fixed
Enterprise — default	Contact sales Let's talk per month	Flat · per month	Standalone · Contact sales

Plain

See full pricing history

USD · US · source: www.plain.com

Plan	Pricing	Charged by	Offer type
Foundation — default	USD 35 monthly · USD 35 / month with annual commitment $35/month, billed yearly	Seat · $35 /month 1 seat + $35/additional seats start	Standalone · Fixed

What each plan includes

Feature names follow each vendor’s own pricing page, so verify the wording before treating them as exact equivalents.

Letterbook

Starter — default

Highlights Seats: 3 seats

Included
Highlights Tickets per month: 300 tickets / month

Included
Highlights Integrations: Integrate your database & Stripe

Included
Highlights Inbox: Unified inbox for all your channels

Included

Growth — default

Highlights Seats: 10 seats

Included
Highlights Tickets per month: 1,000 tickets / month

Included
Highlights Channels and integrations: All channels and integrations

Included
Highlights Support: Priority support

Included

Enterprise — default

Highlights Seats: Custom seats

Included
Highlights Tickets per month: 3,000+ tickets / month

Included
Highlights Security: SSO & SAML

Included
Highlights Account management: Dedicated account manager

Included

Plain

Foundation — default

Highlights User seats: 1 seat + $35/additional seats start

Included
AI features Credits included: 2,000/mo

Included
Highlights Channels: Slack, email, in-app channels

Included
AI features Ari AI agent: included

Included
Highlights Integrations: Linear, Jira integrations

Included
Highlights Help Center, Knowledge Base: included

Included
Highlights Customer cards: included

Included
AI features AI workflows: included

Included
AI features Sidekick AI assistant: included

Included
Highlights Support: Email + chat

Included

How their prices changed

Each dated row shows the public prices observed when that vendor’s pricing page changed.

Letterbook

August 27, 2026 Source
- Starter — default: USD 50 monthly · USD 50 / month with annual commitment
- Growth — default: USD 200 monthly · USD 200 / month with annual commitment
- Enterprise — default: Contact sales

Plain

August 27, 2026 Source
- Foundation — default: USD 35 monthly · USD 35 / month with annual commitment