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Warmbly
What Warmbly is
Warmbly is an open-source cold outreach platform that brings email warmup, sending, campaigns, an inbox, analytics and CRM together. Campaign sequences can branch according to opens, clicks and replies, use A/B variants, and send follow-ups in the same conversation thread. You can set weekday working-hour sending windows for a chosen timezone. Its unified inbox classifies replies, bounces, out-of-office messages and clicks across connected mailboxes.
Warmbly runs on the web, offers an API and can be self-hosted under the Apache 2.0 license. If a self-hosted installation connects to Warmbly Cloud for warmup, campaigns, contacts and inbox data stay on the self-hosted server. Integrations include HubSpot, Salesforce, Pipedrive, Close, Zapier, Make, n8n, Slack, Discord, Calendly and Cal.com. Google Sheets lead syncing is available on demand. The platform lists 21 webhook event types, with HMAC-SHA256 signatures, endpoint event filters and secret rotation.
Warmbly names founders, agencies, sales teams, recruiters and fundraisers as intended users. It offers a free warmup pool for up to 10 mailboxes and paid plans. The Starter plan is $23 a month when billed annually; the pricing note also lists paid plans from $29/mo. Warmbly is associated with Mindroot Ltd, based in London, United Kingdom.
Who it suits
Warmbly suits founders, agencies, sales teams, recruiters and fundraisers managing outreach across mailboxes. Its branching sequences, reply classification, integrations and optional self-hosting may fit teams that want outreach and CRM tools in one platform.
What it does well
- Sequences branch on opens, clicks and replies, with A/B variants.
- Weekday sending windows can follow a selected timezone.
- Inbox classifies replies, bounces, out-of-office messages and clicks.
- Integrations include major CRMs, automation tools and calendars.
- Self-hosting is available under the Apache 2.0 license.
- Webhooks support signatures, event filters and secret rotation.
What to know first
- The free warmup pool supports up to 10 mailboxes.
- Starter, Grow and Business list a 100-per-day cold-send cap per mailbox.
- Enterprise pricing is volume-based and requires contacting sales.
Limits
The free warmup pool supports up to 10 mailboxes. Starter is $23 a month billed annually and lists 150 emails per day; the plan matrix also lists a 100-per-day cold-send cap per mailbox for Starter, Grow and Business.
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Warmup pool · Free | Up to 10 mailboxes warming in the pool | Free |
| Warmup pool · Unlimited | Unlimited mailboxes · paid tier partners first | $15 a month |
| Starter | annually · 20% off · Unlimited mailboxes · unlimited warmup · 150 emails / day · unified inbox and reply detection · sequences with branching | $23 a month |
| Business | annually · 20% off · Unlimited mailboxes · unlimited warmup · 15,000 emails / day · sending kept apart from other customers · team roles and audit log · priority support | $263 a month |
| Grow | annually · 20% off · Unlimited mailboxes · unlimited warmup · 3,000 emails / day · CRM, pipelines, deals and tasks · API and HMAC-signed webhooks · custom tracking domain | $71 a month |
| Enterprise | volume-based · contact sales · 15,000+ emails / day · SSO / SAML · SCIM · custom contract · dedicated CSM + SLA | On request |
As warmbly.com lists them, read 7 Oct 2026. The maker's own page has the final word.
Getting started
- Visit warmbly.com.
- Choose the free warmup pool or review the paid plans.
- Use Warmbly on the web, through its API, or self-host it under Apache 2.0.
- Connect mailboxes and configure warmup or campaign sending.
- Connect a listed integration if needed; request Google Sheets lead syncing on demand.
Verdict
Choose Warmbly if you want outreach sequences, warmup and reply handling in one platform, with a self-hosted option and a broad set of listed integrations. The free option is a warmup pool rather than a full campaign plan. Look elsewhere if you need a free campaign plan or sending beyond the listed per-mailbox cap on Starter, Grow or Business.
Questions
Is Warmbly open source?
Yes. Warmbly is available under the Apache 2.0 license and can be self-hosted for free.
What does the free plan include?
The free warmup pool supports up to 10 mailboxes warming in the pool.
How much does Warmbly cost?
The Warmup pool · Unlimited plan is $15 a month. Starter is $23 a month when billed annually; the pricing note says paid plans start from $29/mo.
Which platforms can I use?
Warmbly lists API, self-hosted and web platforms.
What integrations are listed?
They include HubSpot, Salesforce, Pipedrive, Close, Zapier, Make, n8n, Slack, Discord, Calendly and Cal.com. Google Sheets lead syncing is available on demand.
Who makes Warmbly?
The site footer identifies Mindroot Ltd as the company behind Warmbly and gives its address as 71-75 Shelton Street, London WC2H 9JQ.
Facts from Warmbly's own pages
- 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, 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, 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, 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, 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, 7 Oct 2026
- Headquarters
- London, United Kingdom · warmbly.com, 28 Sept 2026
- Inbox
- The unified inbox classifies replies, bounces, out-of-office messages and clicks across connected mailboxes. · warmbly.com, 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, 7 Oct 2026
- Product
- Warmbly is an open-source cold outreach platform that combines email warmup, sending, inbox, campaigns, analytics and CRM. · warmbly.com, 7 Oct 2026
- Scheduling
- Campaigns can send within weekday working-hour windows configured for a selected timezone. · warmbly.com, 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, 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, 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, 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, 7 Oct 2026
- Use cases
- Warmbly identifies founders, agencies, sales teams, recruiters and fundraisers as intended users. · warmbly.com, 7 Oct 2026
Where Warmbly stands on Freedom251
- Cold Email Software#11 of 35