Instantly alternative

The open-source Instantly alternative

Send cold email from your own mailboxes with per-mailbox limits, then let an AI CRM read every reply and draft the answer. Instantly is a mature, hosted cold email platform with a lead database. AgentSDR is the self-hosted one.

Star on GitHub Self-host it

agentsdr.your-company.com/crm/actions

Action required

Every reply the AI has classified, with the answer it drafted. Approve, edit or reclassify.

In the queue

replies and follow-ups due

Drafts to review

written by your model

Follow-ups due

past their due date

Errors

nothing failed today

Queue

Newest reply first. Hover a reply or a draft to read it whole.

The short version

AgentSDR and Instantly, in a line each

Instantly is a hosted cold email platform with unlimited sending accounts, warm-up, a lead database and an AI CRM.

AgentSDR

Cold email from Google Workspace, plus LinkedIn and WhatsApp, and an AI CRM that classifies and drafts replies.

Instantly

Deliverability tooling, unlimited accounts and warm-up, a lead database and AI agents, hosted for you.

Side by side

AgentSDR vs Instantly, feature by feature

Both centre on cold email from your own accounts and an inbox that handles replies. Instantly has more email infrastructure around it. AgentSDR has more channels and the code.

AgentSDR compared with Instantly, feature by feature
Feature	AgentSDR	Instantly
Where it runs	YesSelf-hosted. AGPL-3.0 source on your own server and database	Hosted by Instantly
How you pay	No seat or contact fees from AgentSDR. You pay for your server and the services you connect	Separate plans for outreach, bundles and a credit system for its lead database and AI tools. Unlimited team seats on its CRM
Sending accounts	PartlyGoogle Workspace mailboxes only, each with its own daily limit and sending hours	YesUnlimited email accounts and unlimited warm-up on its plans
Email warm-up	NoNot built in. Low per-mailbox defaults instead: 30 a day, 18 to 24 minutes apart	YesEmail warm-up included
Deliverability tools	PartlyBounce suppression, one-click unsubscribe and reply stop. No inbox placement testing	YesInbox placement and deliverability management tools
Lead database	NoNo built-in contact database. You import lists or connect providers with your own keys	YesA B2B lead database of 450M+ contacts per its site, paid with credits
Unified inbox	YesOne inbox for email, LinkedIn and WhatsApp replies	YesA master inbox for emails, calls, SMS and tasks
AI on replies	YesReplies classified, with a reason, and answered with drafts you approve	YesAn AI Reply Agent for handling responses
Other channels	YesLinkedIn and WhatsApp campaigns, plus recorded WhatsApp calls	PartlyIts CRM page lists email, calling and SMS
Pipeline and analytics	YesA pipeline and analytics by channel for replies, meetings and customers	YesTracking of opportunities, pipeline, conversions and revenue

“Not compared” means we could not confirm it from Instantly’s own site, so we have not claimed either way.

How AgentSDR works

What you get instead of Instantly

Cold email, kept small

Limits that look like a person wrote the email

Each mailbox has its own daily cap, sending window and signature. Mails go out one at a time with a random gap, and a lead stays with the mailbox that first wrote to them.

30 emails a day per mailbox by default
A random 18 to 24 minute gap between sends
Follow-ups in the same thread when the subject is left blank

The AI inbox

Every reply read, sorted and drafted

Replies are classified with a visible reason, moved through your pipeline and answered with a draft from your knowledge base. You review and send, so nothing leaves without you.

Out-of-office and bounces kept out of the way
A reply on LinkedIn or WhatsApp also stops email follow-ups
Keyboard-first review in Action required

channels from one lead record: email, LinkedIn, WhatsApp: 3
enrichment providers you can connect with your own keys: 15
emails a day per mailbox by default, changeable: 30
per seat, sender or contact from AgentSDR: $0

Being fair

Where Instantly is the better choice

Open source is not the right answer for everyone. If one of these describes you, use the other tool.

You send at high volume from many accounts
Instantly lists unlimited email accounts, warm-up and inbox placement tools. AgentSDR is built for deliberate, per-mailbox volume and warms nothing up.
You need contacts included
Instantly has a lead database inside the product. AgentSDR needs a list you bring or a provider you connect.
You use Outlook or other providers
AgentSDR sends only from Google Workspace mailboxes today.
You want a managed service
Instantly is hosted, with product support and a managed option. AgentSDR is software you run.

Why teams switch

Reasons to move from Instantly to AgentSDR

Email is one of three channels
LinkedIn and WhatsApp campaigns and recorded calls share the same lead record and inbox.
No usage meter from AgentSDR
No plan tiers, email caps or credits from us. Your limits are the Sending rules you set.
Your mailbox data stays yours
Messages, leads and suppression lists live in your own PostgreSQL database.
AI you can steer
Replies are drafted with your own OpenRouter key and knowledge base. Pick the model, and approve every send.

Getting started

Moving from Instantly

A day of work for a typical list. Nothing here touches your old account until you decide to close it.

01
Connect Google Workspace
Set up one service account with domain-wide delegation and add each mailbox by address.
02
Bring your leads and suppressions
Export leads from Instantly as CSV and import them into a campaign. Include bounced and unsubscribed addresses so they stay suppressed.
03
Rebuild the sequence
Write the first email and timed follow-ups with merge fields and spin text, then preview a real lead.
04
Launch and answer
Replies arrive classified in Action required, with a draft ready to review.

FAQ

Questions, answered

Is there an open-source alternative to Instantly?

AgentSDR is open source under AGPL-3.0 and sends multi-step cold email from your Google Workspace mailboxes. It does not include email warm-up, inbox placement tests or a contact database, which Instantly offers.

How many emails can AgentSDR send per mailbox?

30 a day by default, with a random 18 to 24 minute gap, only inside the mailbox's sending hours. You can change the rule for your organization or per mailbox.

Does AgentSDR handle bounces and unsubscribes?

Yes. Delivery failure reports are read from your mailbox and the address is suppressed. Every email carries an unsubscribe link and a one-click header, and suppressed addresses are never mailed again from any campaign.

Does AgentSDR have an AI reply agent?

It classifies every reply, shows the reason and drafts an answer from your knowledge base. It sends only what you approve. It can move a lead forward on its own; anything else waits for you.

Can I use Outlook or SMTP mailboxes?

Not yet. Email goes out through Google Workspace mailboxes only.

Do I need to warm up mailboxes?

A new mailbox should be warmed up outside AgentSDR before you start. The product keeps volume low by default but does not generate warm-up traffic.

Instantly is a trademark of its owner. Comparison based on publicly available information as of October 2026.

Cold email you can read the code of

Connect Google Workspace, send from mailboxes you own and let the AI inbox do the sorting.