Software Alternatives, Accelerators & Startups

SigmaOS VS ForthWrite

Compare SigmaOS VS ForthWrite and see what are their differences

SigmaOS logo SigmaOS

The new home for your internet ๐Ÿก

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
  • SigmaOS Landing page
    Landing page //
    2022-04-27
  • 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.

SigmaOS

Pricing URL
-
$ Details
freemium $10.0 / Monthly (Pro)
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

SigmaOS features and specs

  • Innovative Design
    SigmaOS offers a unique and modern user interface designed to improve productivity by organizing web tasks more efficiently.
  • Focus on Productivity
    The browser focuses on streamlining workflows and reducing distractions, allowing users to manage tasks and tabs more effectively.
  • Built-in Collaboration Features
    SigmaOS includes collaboration tools that allow users to easily share sessions and collaborate with team members in real time.
  • Customizability
    Users can customize their browsing experience by organizing workspaces and tab layouts according to their preferences.
  • Integration with Third-party Tools
    It integrates easily with popular productivity tools and services, enhancing its utility for power users.

Possible disadvantages of SigmaOS

  • Limited Extension Support
    As a relatively new browser, SigmaOS may not support as many browser extensions as more established browsers like Chrome or Firefox.
  • Learning Curve
    Users familiar with traditional browsers might need some time to adapt to SigmaOS's unique interface and features.
  • Platform Availability
    SigmaOS might be available only on certain platforms (like macOS), limiting its accessibility for users on different operating systems.
  • Subscription-based Model
    Some advanced features may require a subscription, which could be a drawback for users seeking free browsing solutions.
  • Performance Concerns
    Being a newer product, there may be performance issues or bugs that are still being ironed out over time.

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 ForthWrite

Overall verdict

  • I don't have verified information about a product called ForthWrite (forthwrite.ai). I cannot confirm its features, quality, or reputation, so I'm unable to provide an accurate assessment of whether it's good.

Why this product is good

  • No reliable data available on this specific product in my knowledge base
  • This may be a newer product, a niche tool, or possibly a fictional/hypothetical name
  • Providing details without verified information could result in inaccurate or fabricated claims

Recommended for

  • Unable to determine without verified product information
  • Consider checking the official website, user reviews on platforms like G2 or Trustpilot, and independent tech review sites for accurate details

SigmaOS videos

SigmaOS: A Browser Reimagined

More videos:

  • Review - SigmaOS the newest browser to take on Chrome and Firefox

ForthWrite videos

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

Add video

Category Popularity

0-100% (relative to SigmaOS and ForthWrite)
Web Browsers
100 100%
0% 0
Email
0 0%
100% 100
Productivity
100 100%
0% 0
Email Productivity
0 0%
100% 100

Questions & Answers

As answered by people managing SigmaOS 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 SigmaOS and ForthWrite. For example, how are they different and which one is better?
Log in or Post with

Reviews

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

SigmaOS Reviews

We have no reviews of SigmaOS yet.
Be the first one to post

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, SigmaOS seems to be more popular. It has been mentiond 13 times 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.

SigmaOS mentions (13)

  • Ask HN: Arc is dead, where should we move now?
    Iโ€™ve been using https://sigmaos.com/ for the past couple of years, and it works very similar. - Source: Hacker News / about 1 year ago
  • Ask HN: What macOS apps/programs do you use daily and recommend?
    Has anyone used the SigmaOS browser? I was surprised to learn that Orion isn't the only new WebKit browser project right now: https://sigmaos.com. - Source: Hacker News / about 2 years ago
  • Anyone knows what browser this is where you can reduce a browser to it's edges? I thought it was sidekick but apparently not.
    SigmaOS. Itโ€™s borders colors also matches the website theme, so it looks really cool. Source: over 2 years ago
  • Chrome Extensions into Safari
    You're better off checking out something like Orion (https://kagi.com/orion/) or SigmaOS (https://sigmaos.com) if you're looking for a Safari like experience. Both of them are built on top of WebKit (same as Safari) but they support Chrome + Firefox extensions. Source: over 2 years ago
  • Unreliable Safari
    Other alternatives with slightly different UX concepts are Arc & SigmaOS. Tried them both, while they bring interesting things for productivity workflows, just couldn't find the UX comfort of traditional browsers (but they're both great and worth checking them out!). Source: over 3 years ago
View more

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 SigmaOS and ForthWrite, you can also consider the following products

Sidekick Browser - The fastest browser for work ever made

ReclaimAI - Helps users prioritize their work and personal calendars

Brave - Fast and secure, ad and tracker blocking browser.

Superhuman - Superhuman is an email management tool.

Google Chrome - Google Chrome is a fast, secure, and free web browser, built for the modern web. Give it a try on your desktop today.

Shortwave - Email smarter & faster with a reinvented experience for your Gmail