Underfive
AI inbox agents that answer cold email and LinkedIn replies in under 5 minutes and book meetings on your calendar, priced per reply.
From $60/mo Free trial MCP server API
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Bottom line
Underfive puts every cold email and LinkedIn reply in one inbox and has AI agents answer them in under five minutes and book the meeting. It suits agencies and recruiting firms running outbound for clients who lose meetings to slow replies. Plans start at $60 a month for 200 credits, and new accounts get 50 free credits with no card.
Stands out for: Pricing follows the replies its agents handle rather than seats or mailboxes, so a small desk can start at $60 a month where Master Inbox starts at $599. It also ships its own hosted MCP server, so an AI assistant like Claude can read threads and approve or send replies.
Watch out for: Credits run out faster on high volume or chatty threads, since every reply read costs half a credit and every draft costs one. The API, webhooks and MCP server start on the $150 Growth plan, and the entry plan has a single workspace.
Overview
Underfive is a unified inbox with AI inbox agents for cold email and LinkedIn outreach. You keep your sequencer, paste an API key or connect Gmail and Outlook, and for most tools Underfive registers the reply webhook for you so replies start landing in one place.
You point each agent at your website, pricing and FAQs, connect a calendar and decide which reply categories send on their own and which wait for approval. When a lead is interested, the agent offers real times, handles the back and forth and sends the invite, and quiet threads get a follow-up.
Agencies give every client a separate workspace with its own agents, knowledge, calendar and Slack channel. CRM sync with GoHighLevel and HubSpot moves deals between stages when a lead is interested or books.
Plans are priced on credits: 0.5 to read and classify a reply and 1 to draft a response. The vendor also offers a managed service in which its own team works the inbox and books meetings for you.
Who it's for
Best for
- Agencies booking meetings for several clients
- Recruiters who miss replies outside working hours
- Teams running both cold email and LinkedIn outreach
- Teams that want AI drafts approved in Slack
Not ideal for
- Teams that want flat pricing regardless of volume
- Senders who want no automated replies at all
- Users who need API access on the entry plan
Key features
Unified inbox. Email and LinkedIn replies from Smartlead, Instantly, EmailBison, PlusVibe, Lemlist, HeyReach, Expandi, Aimfox and GetSales land in one inbox, with no cap on mailboxes.
Replies in under five minutes. Inbox agents read the whole thread and answer in your voice, day and night, in any language, from the original mailbox or LinkedIn profile.
Meeting booking. Agents offer real times from Google Calendar or Outlook, or use your Calendly or Cal.com link, send the invite and round-robin across reps.
Approvals per category. Set each reply category to auto-send or require approval, and approve or edit drafts in the app or in Slack.
Client workspaces. Each client gets its own agents, knowledge base, calendar and Slack channel.
API and MCP server. From the Growth plan, a REST API, webhooks and a hosted MCP server let Claude and other clients read threads and approve or send replies.
AI features
| What the AI does | Plan |
|---|---|
Only features named in the vendor's own documentation. Anything sold separately is marked as an add-on.
MCP server
https://docs.underfive.ai/mcp
First-party MCP at docs.underfive.ai. https://docs.underfive.ai/mcp.
Setup steps and live status MCP Directory Check your stack in the MCP readiness checker
Pricing
| Plan | Price | What you get |
|---|---|---|
| Professional | $60/mo | 200 credits, 1 workspace |
| Growth | $150/mo | 500 credits, 5 workspaces, API, webhooks, MCP |
| Business | $250/mo | 1,000 credits, 10 workspaces |
| Agency | $500/mo | 2,500 credits, unlimited workspaces |
Underfive prices on credits used by its agents, not on seats or mailboxes: reading a reply costs 0.5 credits and drafting a response costs 1 credit. Professional is $60 a month for 200 credits and one workspace. Growth is $150 a month for 500 credits and five workspaces and adds the API, webhooks and MCP server. Business is $250 a month for 1,000 credits and ten workspaces. Agency is $500 a month for 2,500 credits, unlimited workspaces and custom integrations. Paying annually saves 20%, custom plans are available above 2,500 credits, and a managed service is offered where the vendor's team works the inbox. New accounts start with 50 free credits and no credit card. Confirm current terms on the vendor site.
Checked 4 Nov 2026. Vendors change prices without notice.
Is Underfive expensive?
Underfive does not publish a price. It is one of 22 quote-based tools among the 144 outreach tools in our directory. 30 have a free tier, and those with a public price typically start around $49 a month.
- 22 quote-based
- 30 free tier
- 122 public price
Worked out automatically from every outreach listing, so it updates as the directory changes.
Pros and cons
Pros
- Low entry price, priced per reply
- Email and LinkedIn in one inbox
- Hosted MCP server and API
Cons
- Credits can run out at volume
- API and MCP from $150 a month
- One workspace on the entry plan
Integrations
Smartlead Instantly EmailBison PlusVibe Lemlist HeyReach HubSpot Slack
What's new at Underfive
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How Underfive compares
See all Underfive alternatives, with what each one does differently and a head to head for every pairing.
| Tool | Free tier | From | MCP | API | Compare |
|---|---|---|---|---|---|
| | – | $60/mo | ✓ | ✓ | |
| | – | $1.50/person prospected | – | – | Compare |
| | – | $40/mo | – | – | Compare |
| | – | $37.60/mo | ✓ | ✓ | Compare |
$1.50/person prospected
AiSDR runs the whole outbound sequence with AI, while Underfive keeps your sequencer and only handles what happens after the reply.
$40/mo
Salesforge is a sequencer with its own AI agent, while Underfive plugs into Smartlead, Instantly and others you already use.
$37.60/mo MCP API
Instantly has its own AI reply features for Instantly campaigns, while Underfive covers several sequencers and LinkedIn tools in one inbox.
Your next step
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