TraceAgently
LangSmith
Langfuse
Helicone AI
Arise
AgentNotch
Balagan Agent
Deeptracer.dev
ForthWrite
ReclaimAI
Superhuman
Shortwave
Serif AI
Gemini
Gmail
LIAM
TraceAgently is an observability API for AI agents. Drop a few lines into any agent and get a real-time dashboard showing every thought, tool call, tool result, and error in the exact order they happened.
AI agents fail silently. Your logs show nothing useful. You have no idea if your agent called the wrong tool, looped, or hit a token limit.
Raw OpenAI, Claude, Gemini, LangChain, CrewAI, or any custom loop. No framework lock-in.
Free tier: 5,000 events/month, no credit card.
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
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.
TraceAgently ForthWriteTraceAgently's answer
Python and Node SDKs
ForthWrite's answer:
Next.js, React, Supabase, Anthropic Claude, OpenAI, Stripe, Vercel, Chrome Extensions API
TraceAgently's answer
Most observability tools wrap your LLM calls. TraceAgently works with any agent loop you write yourself, not just supported frameworks. You instrument what matters and see it live.
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.
TraceAgently's answer
No framework lock-in, no SDK wrapping your entire stack. Works in 5 minutes and has a genuinely free tier.
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.
TraceAgently's answer
Developers building AI agents who need to debug what's happening inside the loop.
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.
TraceAgently's answer
Built it after shipping agents that worked in testing and broke in production with no useful logs to debug them.
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.
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.
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Langfuse - Langfuse is an open-source LLM engineering platform that helps teams collaboratively debug, analyze, and iterate on their LLM applications.
Superhuman - Superhuman is an email management tool.
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