Autonomous AI SDR that runs LinkedIn and WhatsApp outreach and replies for you
Second Brain Labs is an autonomous AI SDR that carries LinkedIn and WhatsApp conversations end to end, optionally from rented sender profiles rather than your own account.
Best for
Small teams that want an AI to carry LinkedIn conversations end to end without using their own account.
Not great for
Teams who want the prospect to meet their own brand and face, since outreach can run from Fractional SDR profiles belonging to other people.
Starting price
$99/seat/mo
Pricing model
Per seat
Free trial
Not advertised
Platforms
Web app, api
Founded
2023
Headquarters
India
Second Brain Labs, in plain terms
Second Brain Labs, which trades as Sbl.so, is an autonomous AI SDR for LinkedIn and WhatsApp. Its core product is a reply engine the company calls the Persuasion Chat Model: the AI opens the conversation, asks qualifying questions, answers objections, follows up and books meetings, and raises a Human Intervention flag when it cannot answer something. Lead sourcing supports CSV, Sales Navigator URLs, comment-to-DM capture on posts, post-likes extraction and a plain-text ICP description that returns matching leads. Signals cover job changes, funding and competitor engagement. AI voice cloning from a short sample ships on the Pro tier, and images, videos and PDFs can be attached inside outreach. There is a built-in CRM with two-way sync to HubSpot, Salesforce, Pipedrive and Zoho, a public REST API and a Claude MCP server. The structural point buyers should understand is who sends the messages. Per the founder's posts on AppSumo, outreach can run from Fractional SDR profiles, which are real verified LinkedIn accounts from the company's affiliate network whose owners are paid a fixed monthly fee starting around $39 to allow their profile to be used, with the headline and banner set to the customer's brand tone. Your own account is not used. Published limits are 75 requests and 200 messages per profile per day.
Key features
- Persuasion Chat Model that runs replies end to end with a human intervention flag
- Fractional SDR sender profiles, warmed up and rotated automatically
- AI voice cloning for voice notes in outreach and in replies
- Signals for job changes, funding and competitor engagement
- Built-in CRM with two way sync to HubSpot, Salesforce, Pipedrive and Zoho
- Unified inbox across connected accounts for the whole team
- Fixed caps of 75 requests and 200 messages per profile per day
- Public REST API with webhooks and a Claude MCP server
Pros
- The AI runs the whole conversation, asks qualifying questions, handles objections and raises a Human Intervention flag when it is stuck
- AI voice cloning from a 10 to 30 second sample on the Pro tier
- WhatsApp is a live second channel alongside LinkedIn
- Six lead import methods, including comment to DM capture and a plain text description of your ideal customer
- An unusually generous trial: free until your first meeting, or 3 positive replies, or 300 outreaches, with no card
- Public REST API with webhooks plus a Claude MCP server
Cons
- Outreach can run from Fractional SDR profiles, real LinkedIn accounts from their affiliate network paid a fixed fee starting around $39 per month, per their founder's AppSumo answers
- Their homepage advertises a 90% money-back guarantee with an asterisk, while their published refund policy describes a $7 trial refund and a 15 day setup fee window, and their terms state subscription fees are non-refundable, checked July 2026
- Public review coverage is thin: 66 reviews on AppSumo, none on Product Hunt, and no Trustpilot listing found in July 2026
- A verified AppSumo purchaser reported in July 2026 that the dashboard is not usable on a mobile device
- Leads are metered at 1,000 to 2,000 per month by tier, and no email finder or verifier is advertised
Cost at scale
About $47 per seat per month, computed from Pro at $189 for 4 included seats, with extra seats at $39
Users claimed
5,000+ companies and 50M+ messages sent (claimed)
| Plan | Price | Limits | Includes |
|---|---|---|---|
| Starter | $99 per month | 1,000 ICP matched leads per month, 2 outreach seats, 2 team members | 2 outreach seats, extra at $39, 1,000 ICP matched leads per month, LinkedIn and WhatsApp, MCP, API and webhooks |
| Pro | $189 per month | 2,000 leads per month, 4 seats, 10 team members | 4 seats included, extra at $39, 2,000 leads per month, Premium signals, Rich media with AI cloned voice, Built-in CRM with export |
| Elite | $997 per month | 500 hyper curated leads, LinkedIn only, listed as coming soon and invite only | Listed as coming soon, invite only, 500 hyper curated leads, LinkedIn only |
| Enterprise | Custom quote | Quoted per account | Contact their sales team |
From their published pricing, July 2026 (check their pricing). Starter is $99 per month for 2 outreach seats and Pro is $189 per month for 4 seats, with extra seats at $39 per month. An Elite tier at $997 is listed as coming soon and invite only. An AppSumo lifetime deal was also live in 2026 with credit-metered tiers.
What reviews praise
- An AppSumo rating of 4.4 from 66 reviews, 53 of them five star
- Named customers with named executives on record rather than anonymous logos
What reviews flag
- A verified purchaser reported unanswered support questions on Slack in July 2026
- Another reported that the dashboard is not usable from a mobile device
- A one star reviewer described a steep learning curve and add-on costs, and the founder replied publicly offering a call
Distilled from public reviews and community threads. Not Weezly's opinion, and not a rating.
API access
Public REST API with webhooks and OAuth, plus a Claude MCP server
Data export
Built-in CRM with export on the Pro tier, plus two way sync to HubSpot, Salesforce, Pipedrive and Zoho
Automation platforms
Zapier, n8n and Make, plus static and custom webhooks
Integrations
HubSpot
Salesforce
Pipedrive
Zoho
SlackNotion
Zapier
n8n
Make
Claude- HQ
- Bengaluru, India
- Founded
- 2023
- Employees
- Around 108, reported April 2026
- Leadership
- Shubham Kumar, co-founder and chief executive, with co-founder Ayush Singh
- Company page
The full comparison
Weezly vs Second Brain Labs: every claim, sourced.
AI digital workers for outbound prospecting and inbound phone qualification
AI SDR that prospects, writes and sends across email and LinkedIn, then books the meeting
AI BDR agent that sources, enriches, emails and books meetings, sold by quote
Platform for building AI agent teams, with prebuilt GTM and AI SDR agent templates
Either yours or a Fractional SDR profile. Per the founder's answers on AppSumo, those are real verified LinkedIn profiles from the company's affiliate network whose owners are paid a fixed monthly fee starting around $39 to allow their account to be used, with the headline and banner set to your brand tone. The stated benefit is that your personal account is never used for outreach.
Yes. Recording a 10 to 30 second sample creates a cloned voice that can send voice notes in initial outreach and in chat replies. The feature is gated to the Pro tier.
It can attach video, image and PDF files inside outreach, and the AI picks what fits the conversation. It does not generate a new video per lead, and face cloning is not advertised.
Their pricing page offers use of the product for free until your first meeting, or 3 positive replies, or 300 outreaches, with no credit card required. One of their comparison pages instead says a 7 day free trial, so check the pricing page.
Read the refund terms. The homepage advertises a 90% money-back guarantee with an asterisk, while the published refund policy as of July 2026 describes a $7 trial refund and a 15 day setup fee window, and the terms of use state that subscription fees are non-refundable. Their public review base is also thin, with 66 reviews on AppSumo at 4.4 out of 5.
One of these tools is ours.
Weezly is in this directory too: LinkedIn outreach with AI clone videos, a 300M+ leads database and booking, from $59 per month. See if it earns a spot in your stack.