Warmbly
warmbly.com
What it is
Warmbly is an open-source cold outreach platform that brings email warmup, campaign sending, a unified inbox, analytics, and CRM together. Campaign sequences can branch based on opens, clicks, or replies, include A/B variants, and send follow-ups in the same conversation thread. Sending can be restricted to weekday working hours in a selected 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 a self-hosted installation connects to Warmbly Cloud for warmup, campaigns, contacts, and inbox data remain on the self-hosted server. Integrations include HubSpot, Salesforce, Pipedrive, Close, Zapier, Make, n8n, Slack, Discord, Calendly, and Cal.com; Google Sheets lead sync is available on demand. The free warmup pool supports up to 10 mailboxes. Paid campaign plans include Starter at $23 a month billed annually, with 150 emails per day, and Grow at $71 a month billed annually, with 3,000 emails per day.
Spec sheet
- Product
- Warmbly is an open-source cold outreach platform that combines email warmup, sending, inbox, campaigns, analytics and CRM.Read 7 Oct 2026 · warmbly.com
- 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.Read 7 Oct 2026 · warmbly.com
- 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.Read 7 Oct 2026 · warmbly.com
- Compliance
- Warmbly describes its data handling as GDPR-aligned and lists SOC 2 Type II and ISO 27001 as planned, with no certification claimed.Read 7 Oct 2026 · warmbly.com
- Support
- The pricing page lists community support for Starter, email for Grow, priority support for Business and dedicated support for Enterprise.Read 7 Oct 2026 · warmbly.com
- Headquarters
- London, United KingdomRead 28 Sep 2026 · warmbly.com
- Company
- The site footer identifies Mindroot Ltd as the company behind Warmbly and gives its address as 71-75 Shelton Street, London WC2H 9JQ.Read 7 Oct 2026 · warmbly.com
- API and webhooks
- Warmbly lists 21 event types for webhooks, which use HMAC-SHA256 signatures and support endpoint event filters and secret rotation.Read 7 Oct 2026 · warmbly.com
- Campaigns
- Campaign sequences can branch on opens, clicks and replies, use A/B variants, and send follow-ups in the same conversation thread.Read 7 Oct 2026 · warmbly.com
- 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.Read 7 Oct 2026 · warmbly.com
- Inbox
- The unified inbox classifies replies, bounces, out-of-office messages and clicks across connected mailboxes.Read 7 Oct 2026 · warmbly.com
- Scheduling
- Campaigns can send within weekday working-hour windows configured for a selected timezone.Read 7 Oct 2026 · warmbly.com
- 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.Read 7 Oct 2026 · warmbly.com
- 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.Read 7 Oct 2026 · warmbly.com
- Use cases
- Warmbly identifies founders, agencies, sales teams, recruiters and fundraisers as intended users.Read 7 Oct 2026 · warmbly.com
Plans and prices
Warmup pool · Free Free Up to 10 mailboxes warming in the pool Read 7 Oct 2026 · warmbly.com
Warmup pool · Unlimited $15 a month Unlimited mailboxes · paid tier partners first Read 7 Oct 2026 · warmbly.com
Starter $23 a month annually · 20% off Unlimited mailboxes · unlimited warmup · 150 emails / day · unified inbox and reply detection · sequences with branching Read 7 Oct 2026 · warmbly.com
Grow $71 a month annually · 20% off Unlimited mailboxes · unlimited warmup · 3,000 emails / day · CRM, pipelines, deals and tasks · API and HMAC-signed webhooks · custom tracking domain Read 7 Oct 2026 · warmbly.com
Business $263 a month annually · 20% off Unlimited mailboxes · unlimited warmup · 15,000 emails / day · sending kept apart from other customers · team roles and audit log · priority support Read 7 Oct 2026 · warmbly.com
Enterprise Priced on request volume-based · contact sales 15,000+ emails / day · SSO / SAML · SCIM · custom contract · dedicated CSM + SLA Read 7 Oct 2026 · warmbly.com
Strong points and limits
Strong points
- Campaigns branch on opens, clicks, and replies
- Inbox classifies replies, bounces, and other activity
- Self-hosted option uses Apache 2.0
- Free warmup pool supports up to 10 mailboxes
- Webhooks support signatures, filters, and secret rotation
Limits
- Starter, Grow, and Business cap cold sends at 100 per mailbox daily
- Enterprise pricing requires contacting sales
- SOC 2 Type II and ISO 27001 are planned, not claimed
Who it suits
Warmbly names founders, agencies, sales teams, recruiters, and fundraisers as intended users. Its self-hosting option may suit teams that want campaigns, contacts, and inbox data to remain on their own server while using cloud warmup.
Verdict
Warmbly combines warmup and campaign workflows with reply classification, integrations, and a self-hosting option. Check the plan-specific sending limits and annual billing terms before choosing a paid tier.
Where Specifiction places it
- Cold Email Software#25 of 357.8
