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Warmbly
London, United Kingdom
What it is
Warmbly is an open-source cold outreach platform that combines email warmup, campaign sending, a unified inbox, analytics, and CRM. Campaigns can branch according to opens, clicks, or replies, include A/B variants, and send follow-ups in the same conversation thread. Send times can be limited to weekday working hours in a chosen timezone. The inbox classifies replies, bounces, out-of-office messages, and clicks across connected mailboxes. Warmbly is available on the web and through an API, or can be self-hosted under Apache 2.0. When self-hosted data is linked to Warmbly Cloud for warmup, campaigns, contacts, and inbox content stay on the self-hosted server. Integrations include HubSpot, Salesforce, Pipedrive, Close, Zapier, Make, n8n, Slack, Discord, Calendly, and Cal.com. The service lists 21 webhook event types, with HMAC-SHA256 signatures, filters, and secret rotation. A free warmup pool supports up to 10 mailboxes; the Unlimited pool costs $15 a month. Starter is $23 a month when billed annually, and Enterprise pricing is volume-based.
For and against
For
- Sequences branch on opens, clicks, and replies.
- Unified inbox classifies replies and bounces.
- Self-hosting is available under Apache 2.0.
- Webhooks support signatures, filters, and secret rotation.
Against
- Starter has a 100-per-day cold-send cap per mailbox.
- Starter is $23 a month when billed annually.
- Enterprise pricing is volume-based and requires contacting sales.
The verdict
Warmbly brings warmup, campaign sequences, inbox handling, and CRM together, with both hosted and self-hosted options. Its plan limits and billing terms differ, so check the sending caps and pricing structure for the intended use.
Who it suits
Warmbly names founders, agencies, sales teams, recruiters, and fundraisers as intended users. Self-hosting may suit teams that want campaigns, contacts, and inbox data to remain on their own server.
Plans and prices
Warmup pool · Free
Up to 10 mailboxes warming in the pool
Read 7 Oct 2026 · warmbly.com
Warmup pool · Unlimited
Unlimited mailboxes · paid tier partners first
Read 7 Oct 2026 · warmbly.com
Starter
Unlimited mailboxes · unlimited warmup · 150 emails / day · unified inbox and reply detection
Read 7 Oct 2026 · warmbly.com
Grow
Unlimited mailboxes · unlimited warmup · 3,000 emails / day · CRM, pipelines, deals and tasks
Read 7 Oct 2026 · warmbly.com
Business
Unlimited mailboxes · unlimited warmup · 15,000 emails / day · sending kept apart from other customers
Read 7 Oct 2026 · warmbly.com
Enterprise
15,000+ emails / day · SSO / SAML · SCIM · custom contract
Read 7 Oct 2026 · warmbly.com
On the record
- API and webhooks
- Warmbly lists 21 event types for webhooks, which use HMAC-SHA256 signatures and support endpoint event filters and secret rotation.warmbly.com · read 7 Oct 2026
- Campaigns
- Campaign sequences can branch on opens, clicks and replies, use A/B variants, and send follow-ups in the same conversation thread.warmbly.com · read 7 Oct 2026
- Company
- The site footer identifies Mindroot Ltd as the company behind Warmbly and gives its address as 71-75 Shelton Street, London WC2H 9JQ.warmbly.com · read 7 Oct 2026
- Compliance
- Warmbly describes its data handling as GDPR-aligned and lists SOC 2 Type II and ISO 27001 as planned, with no certification claimed.warmbly.com · read 7 Oct 2026
- Data handling
- Warmbly says it encrypts mailbox credentials and message bodies at rest, while payment card data is held by Stripe and does not touch its servers.warmbly.com · read 7 Oct 2026
- Inbox
- The unified inbox classifies replies, bounces, out-of-office messages and clicks across connected mailboxes.warmbly.com · read 7 Oct 2026
- Integrations
- The listed integrations include HubSpot, Salesforce, Pipedrive, Close, Zapier, Make, n8n, Slack, Discord, Calendly and Cal.com; Google Sheets lead sync is available on demand.warmbly.com · read 7 Oct 2026
- Product
- Warmbly is an open-source cold outreach platform that combines email warmup, sending, inbox, campaigns, analytics and CRM.warmbly.com · read 7 Oct 2026
- Scheduling
- Campaigns can send within weekday working-hour windows configured for a selected timezone.warmbly.com · read 7 Oct 2026
- Security
- Warmbly says it uses TLS 1.2 or above in transit and AWS KMS-backed, per-organization AES-256-GCM encryption at the application layer.warmbly.com · read 7 Oct 2026
- Self-hosting
- The platform is Apache 2.0 and can be self-hosted for free; campaigns, contacts and inbox stay on the self-hosted server when linked to Warmbly Cloud for warmup.warmbly.com · read 7 Oct 2026
- Sending limits
- The pricing matrix lists a 100-per-day cold-send cap per mailbox on Starter, Grow and Business, and a custom cap for Enterprise.warmbly.com · read 7 Oct 2026
- Support
- The pricing page lists community support for Starter, email for Grow, priority support for Business and dedicated support for Enterprise.warmbly.com · read 7 Oct 2026
- Use cases
- Warmbly identifies founders, agencies, sales teams, recruiters and fundraisers as intended users.warmbly.com · read 7 Oct 2026
