The open-source agentic cold email and warmup platform.

Features · How it works · Quick start · Self-hosting · Docs · Community · Support

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Warmbly

Warmbly runs cold email campaigns from the mailboxes you already own and warms them so they keep landing in the inbox. Opens, clicks, and replies land in a shared dashboard the moment they happen, and it's AI-native, so your team and its agents work in it together, live.

https://github.com/user-attachments/assets/378a510a-bb99-425f-925e-04300184938b

Features

• Campaigns - multi-step sequences with per-mailbox caps and spacing
• Unified inbox - every mailbox and reply in one place
• CRM - contacts, pipelines, deals, tasks, meetings
• Warmup - a pool of monitored mailboxes, not throwaway accounts
• Deliverability - bounces, complaints, suppression, inbox placement
• Automations - visual reply playbooks with AI steps
• Integrations - HubSpot, Slack, Zapier, REST API, webhooks
• Realtime - live presence and edits across your team

How it works

Warmbly splits into a control plane (backend API, consumer, Postgres, Redis, and the event bus) that owns all state, and an execution plane of interchangeable Go workers that send and sync mail. Workers never touch Postgres, and outbound mail leaves through each mailbox's own provider, not the worker's IP, so you add throughput by running more workers.

flowchart LR
  MB["Your mailboxes"] --> API
  subgraph CP["Control plane"]
    direction TB
    API["Backend API"] --> DB[("Postgres")]
    API --> BUS{{"Event bus"}}
  end
  BUS --> W1["Worker"]
  BUS --> W2["Worker"]
  BUS --> W3["Worker"]
  W1 --> P["Gmail · Microsoft · SMTP"]
  W2 --> P
  W3 --> P
  P --> R["Recipients"]

Secrets use envelope encryption, with a local AES master key by default or AWS KMS if you prefer. Full write-up in the architecture docs.

Quick start

You need Docker, Go 1.25, and pnpm.

git clone https://github.com/warmbly/warmbly && cd warmbly
make dev

One command brings up the backing services in Docker, applies migrations, seeds demo data, and starts the backend, worker, and dashboard natively. Open http://localhost:5173 and log in with dev@warmbly.com / password123. Full setup lives in the local development guide.

Self-hosting

Warmbly runs with no cloud account of any kind: no AWS, no GCP, no Stripe, no Kafka. One command brings up the whole platform on local, open-source pieces:

git clone https://github.com/warmbly/warmbly && cd warmbly
make up               # or: docker compose up --build

Every external dependency is picked by an environment variable, so you swap in a cloud service only if you want one:

Concern	Self-host default	Optional / cloud
Database	PostgreSQL 16	RDS / Cloud SQL, any Postgres
Cache	Redis (or Valkey)	ElastiCache
Event bus	NATS JetStream	Kafka (-tags kafka)
Blob storage	Filesystem	S3, MinIO, R2, B2
KMS / root key	Local AES master key	AWS KMS
Payments	Off (everything unlocked)	Stripe

Scaling is by mailboxes and workers, not IPs. Reaching it from another machine, connecting Gmail, and day-2 operations are all in the deployment guide.

Documentation

The full docs live at docs.warmbly.com.

Read this	To learn
Local development	Every make target, the native services, and how seeding works
Architecture	How the control plane and workers split the job, plus the encryption model
Deployment guide	Taking it to production and scaling the worker fleet
API reference	Endpoints, auth, permissions, and webhooks

Community

Have a question, found a bug, or want to shape where Warmbly goes next?

• Discord - chat with the team and other senders
• GitHub Issues - report bugs and request features
• X / @WarmblyHQ - follow along for updates and releases
• Email - reach us at team@warmbly.com

Support and enterprise

Note

Need a hand? We are happy to help. Ask in Discord, open a GitHub issue, or email team@warmbly.com, and someone on the team will get back to you.

Running Warmbly at scale, or would you rather we run it for you? We offer enterprise support and managed infrastructure: we can host and operate the whole platform for your organization, help you deploy and scale the worker fleet, tune deliverability, migrate your sending onto Warmbly, and stand behind it with a support agreement built around your team. Tell us what you need at team@warmbly.com or reach out on X.

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Contributing

Pull requests are welcome. Keep each one to a single logical change, and open an issue first for larger design or product changes. Before you open a PR, run the checks for the tree you touched (make fmt and make lint for Go, pnpm typecheck and pnpm lint for the frontends). See CONTRIBUTING.md.

Security

Found a vulnerability? Email team@warmbly.com instead of opening a public issue. We prefer responsible disclosure and credit reporters in the release notes.

License

Apache License 2.0. Copyright 2026 Mindroot Ltd. See LICENSE.