Software Alternatives, Accelerators & Startups

Rainloop VS ForthWrite

Compare Rainloop VS ForthWrite and see what are their differences

Rainloop logo Rainloop

RainLoop is a web based email client.

ForthWrite logo ForthWrite

Email that sounds like you, and gets measurably more like you every week. Drafts in Gmail, Outlook, and the browser. Free to start.
Visit Website
  • Rainloop Landing page
    Landing page //
    2022-10-19
  • ForthWrite Landing Page
    Landing Page //
    2026-06-19
  • ForthWrite Dashboard
    Dashboard //
    2026-06-19
  • ForthWrite In Gmail
    In Gmail //
    2026-06-19
  • ForthWrite Pricing
    Pricing //
    2026-06-19

ForthWrite is an AI email writing assistant for Gmail and Outlook that learns your writing style from your real sent mail. The more you use it, the more it sounds like you. Get smart drafts in seconds, auto-draft replies before you open your inbox, and maintain your personal voice at scale. Free to start, no credit card required. Works inside Gmail and Outlook on the web.

How it works

ForthWrite captures your tone, sentence rhythm, and sign-offs from your actual sent emails, then uses that profile to generate drafts that match how you write, not a generic AI voice. Every draft you edit or send improves the model over time.

Key features

  • Auto-draft: replies waiting in Gmail before you open your inbox
  • Voice matching from your real sent mail, not templates
  • Recipient-aware drafts that adapt to who you are emailing
  • Prompt Lab for version-controlling and A/B testing your persona prompt
  • BYOK support: bring your own API key for Claude, OpenAI, Grok, Mistral, and more
  • Works in Gmail and Outlook on the web, plus a standalone browser widget
  • Training data export and full data portability

Who uses it

Professionals who send high volumes of relationship-critical email: lawyers, financial advisors, recruiters, account executives, founders, and anyone who wants their inbox handled without sounding like a chatbot wrote it.

Pricing

Free tier includes 10 drafts per week with no credit card required. Paid plans start at $12/month and include unlimited drafts, custom persona prompts, and auto-draft.

Rainloop

Pricing URL
-
$ Details
Platforms
-
Release Date
-

ForthWrite

$ Details
freemium $12.0 / Monthly (Standard plan)
Platforms
Web
Release Date
2026 June
Startup details
Country
United States
State
California
City
San Diego
Founder(s)
Curtis Boortz
Employees
1 - 9

Rainloop features and specs

  • User-Friendly Interface
    Rainloop has a clean and intuitive interface that is easy to navigate, providing a good user experience even for those who are not tech-savvy.
  • Lightweight
    Being a web-based email client, Rainloop is lightweight and does not require heavy server resources, which ensures faster loading times and performance.
  • No Database Required
    Rainloop operates without requiring a database, simplifying the installation process and reducing potential points of failure.
  • Support for Multiple Email Providers
    It supports various email protocols such as IMAP and SMTP, and works seamlessly with major email services like Gmail, Yahoo, and Outlook.
  • Modern Features
    Features like two-factor authentication (2FA), PGP encryption support, and integration with third-party services add to security and functionality.

Possible disadvantages of Rainloop

  • Limited Customization
    While Rainloop offers a range of functionalities, its customization options are somewhat limited compared to other email clients.
  • Lacks Advanced Features
    For advanced users, Rainloop might lack certain features like advanced filtering, tagging, or extensive plugin support.
  • Dependency on External Libraries
    Rainloop relies on some external libraries, which could pose security risks or lead to compatibility issues if those libraries are not maintained.
  • Paid Version for Advanced Features
    Some advanced functionalities and features are only available in the paid pro version, such as ActiveSync support and administrative settings.
  • Limited Community Support
    The community around Rainloop is smaller compared to more widely used email clients, which might limit the availability of community-driven support and plugins.

ForthWrite features and specs

  • Voice Matching
    Learns from your real sent mail, not templates
  • Auto-draft replies
    Replies waiting in Gmail before you open your inbox
  • Batch-drafting
    Draft replies for your entire inbox with one click
  • Works in browser
    Gmail, Outlook, and web browsers
  • BYOK support
    Claude, OpenAI, Grok, Mistral, and more
  • Prompt Lab
    Version control and A/B test your persona prompt
  • Free tier
    10 drafts per week, no credit card required

Analysis of Rainloop

Overall verdict

  • Rainloop is a solid choice for users looking for a no-fuss, efficient, and customizable webmail client. Its performance, ease of use, and support for multiple email services make it a popular option.

Why this product is good

  • Rainloop is a lightweight and user-friendly email client that offers seamless integration with various email services such as Gmail, Yahoo, Outlook, and others. It provides a clean and intuitive interface, making it easy for users to navigate. The client supports multiple accounts and has a high level of customization. Additionally, Rainloop is open-source, which means it benefits from community-driven improvements and security reviews.

Recommended for

  • Individuals looking for a lightweight webmail client
  • Users who manage multiple email accounts
  • Open-source enthusiasts
  • Those who require a straightforward and fast interface

Rainloop videos

How to install RainLoop Webmail

More videos:

  • Tutorial - How to install Rainloop Webmail 1.12.0 on Ubuntu 18.04
  • Tutorial - How to install RainLoop E-Mail Client in Ubuntu

ForthWrite videos

No ForthWrite videos yet. You could help us improve this page by suggesting one.

Add video

Category Popularity

0-100% (relative to Rainloop and ForthWrite)
Email
90 90%
10% 10
Writing Tools
0 0%
100% 100
Email Management
100 100%
0% 0
Enterprise Communication
100 100%
0% 0

Questions & Answers

As answered by people managing Rainloop and ForthWrite.

Which are the primary technologies used for building your product?

ForthWrite's answer:

Next.js, React, Supabase, Anthropic Claude, OpenAI, Stripe, Vercel, Chrome Extensions API

What makes your product unique?

ForthWrite's answer:

ForthWrite learns your writing style from your actual sent mail, not a generic prompt. Every draft sounds like you wrote it because it was trained on how you actually write. It also auto-drafts replies before you open your inbox, so your email is partially handled before your day starts.

Why should a person choose your product over its competitors?

ForthWrite's answer:

Most AI email tools give you a blank box and a "write for me" button. ForthWrite builds a voice profile from your sent history and gets more accurate with every draft you edit or send. Unlike ChatGPT or Gemini, it works natively inside Gmail and Outlook with no copy-paste. Unlike Lavender, it writes the draft, not just scores it.

How would you describe the primary audience of your product?

ForthWrite's answer:

Professionals who send high volumes of relationship-critical email and cannot afford to sound generic: lawyers, financial advisors, recruiters, account executives, consultants, and founders managing their own inbox.

What's the story behind your product?

ForthWrite's answer:

Built out of frustration with AI writing tools that produce text that sounds nothing like the person sending it, and as a way to handle large amounts of daily email. The core insight was that your sent mail is the best training data you already have, and no tool was using it.

User comments

Share your experience with using Rainloop and ForthWrite. For example, how are they different and which one is better?
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Reviews

These are some of the external sources and on-site user reviews we've used to compare Rainloop and ForthWrite

Rainloop Reviews

Top 15 Self-hosted open-source free web-based email clients
RainLoop integrates seamlessly with Google, Facebook, Twitter and Dropbox. It features a messages' folder management, media-rich email rendering, advanced attachment management, keyboard shortcuts, multiple email accounts manager, and more.
Source: medevel.com
15 Best iRedMail Alternatives 2021
Rainloop is a modern email server with an easy installation process and support for SMTP and IMAP protocols like STARTTLS and SSL. It delivers a seamless performance and OTA upgrades without the need for a database.
5 open source webmail clients for browser-based email
Next up is Rainloop. Rainloop is a very modern entry into the webmail arena, and its interface is definitely closer to what you might expect if you're used to Gmail or another commercial email client. It comes with most features you've come to expect, including email address autocompletion, drag-and-drop and keyboard interfaces, filtering support, and many others, and it can...
Source: opensource.com

ForthWrite Reviews

  1. curtisboortz
    ยท Founder at ForthWrite ยท
    I built ForthWrite to fix generic AI email, and I still use it every day

    I built ForthWrite because I kept sending emails that sounded like they came from the same generic AI as everyone else. After launching it, I still use it for my own inbox every day, which is about the most honest endorsement I can give.

    The Chrome extension lives inside Gmail and Outlook on the web. Open a thread, hit Alt+Shift+D, and a draft comes back in your voice, not a template. The free tier is real: 10 drafts per week, no API key, no credit card. Voice matching is included on free, because that is the point.

    What keeps it useful compared to Gemini or a chat tab: it learns from what you actually send. Every edit you make before hitting send becomes a signal. Over time the drafts drift closer to how you really write, and the dashboard shows the improvement curve so you can see it happening.

    The web compose surface lets you draft from forthwrite.ai without installing anything, useful for people who want to try before committing to the extension.

    Standard adds recipient-aware and intent-aware drafting plus AI coaching. Pro adds auto-draft (replies waiting when you open Gmail), batch replies, and Prompt Lab for version-controlling your prompts. Teams adds a shared persona and seat-level analytics.

    ForthWrite is not for everyone. If you just need quick replies and tone does not matter, Gemini is free and already in your inbox. ForthWrite is for people where tone does matter: client communication, relationship-driven threads, external correspondence where sounding off costs something real.

    Disclosure: I am the founder and use it daily. Happy to answer questions in the comments.

    ๐Ÿ Competitors: Jace.ai, Fyxer, Mailmeteor
    ๐Ÿ‘ Pros:    Drafts land inside gmail and outlook; no copy-pasting from a chat window|Voice matching is on the free tier, not paywalled behind paid plans|No api key, no credit card to start; free tier runs on a server-side proxy|Learns from every edit you make before sending; drafts improve over time|Full keyboard flow: alt+shift+d to draft in any thread, no mouse required|Byok on paid plans, 9 providers supported, keys encrypted at rest|Web compose at forthwrite.ai works without installing the extension at all
    ๐Ÿ‘Ž Cons:    10 free drafts/week is enough to evaluate, not enough for a heavy inbox|Auto-draft, batch replies, and prompt lab all require the pro tier|Early-stage product; fewer third-party integrations than mature inbox tools|No mobile app: the extension and add-in are desktop-only (chrome on web, or the outlook desktop add-in)

Social recommendations and mentions

Based on our record, Rainloop seems to be more popular. It has been mentiond 1 time since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.

Rainloop mentions (1)

  • Meet PostPilot
    Have a local mail server be part of your development environment, along with a frontend like SquirrelMail or RainLoop. - Source: dev.to / over 1 year ago

ForthWrite mentions (0)

We have not tracked any mentions of ForthWrite yet. Tracking of ForthWrite recommendations started around Jun 2026.

What are some alternatives?

When comparing Rainloop and ForthWrite, you can also consider the following products

Mailpile - Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.

Superhuman - Superhuman is an email management tool.

Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.

Gemini - Gemini, formerly known as Bard, is a generative artificial intelligence chatbot developed by Google. Based on the large language model (LLM) of the same name, it was launched in 2023 in response to the rise of OpenAI's ChatGPT.

Roundcube - Web-based IMAP email client

Lavender - Realtime coaching for sales emails.