The Warmbly Insider’s Guide
Everything we know about Warmbly in one document: what it costs, its grades, getting a refund, getting help and what else to look at. Read it here, or keep a copy.
Warmbly
The Insider’s Guide
Open-source cold email platform with mailbox warmup
Every plan, grade, refund rule and rival among email verification and deliverability tools, read from Warmbly’s own pages.
Made by Warmbly · checked Nov 13, 2026 · toolgpa.com
Contents
- 01WelcomeWhat it is, who it suits, its grades and the ten things to know first
- 02What it costsEvery plan, the free plan, ways to pay less and how prices have moved
- 03What it doesIts main features, where it runs, what it works with and who makes it
- 04Where it standsIts grades against its category, and whether to keep it or make your own
- 05The alternativesThe tools it is most often weighed against, side by side
- 06Quick answersThe questions people ask about it, each answered in a line or two
- 07About ToolGPAWho made this guide, what else is on the site, and how to cite it
ToolGPA put this guide together from Warmbly’s own pages, its app-store listings and our grades. Every fact in it is on Warmbly’s page too, where it is kept up to date. Checked Nov 13, 2026.
Part 01 · Overview
Welcome
What it is, who it suits, its grades and the ten things to know first
2.2
GPA, above 23 of the 61 other email verification and deliverability tools we grade
Warmbly is a cold email platform that warms mailboxes, sends campaigns across them and collects replies in one inbox. It also includes a CRM, a lead finder, an API and automations. The code is Apache 2.0 licensed, so you can self-host it or use the vendor's cloud.
To get you started, here are 9 things to know about Warmbly, taken from its own pages and our grades.
Plans are capped by cold emails a day, and the CRM, API and team roles all sit on the dearer tiers.
- 1
Best for cold email sending with mailbox warmup in one place
Warmbly bundles mailbox warmup, cold campaigns, a shared inbox and placement tests, and the code is open source.
- 2
Paid plans start at $23 a month
As its pricing page puts it: $23 per month, billed yearly ($29 billed monthly).
- 3
You can try it first
14-day free trial, no credit card
- 4
It runs on Web
Web.
- 5
Mailbox warmup
Warmup is unlimited on every paid plan and runs in a shared premium pool, ramping each mailbox's daily volume over time.
- 6
Campaigns and unified inbox
Sequences with follow-ups, branching and A/B tests send across mailboxes, and every reply lands in one inbox with labels.
- 7
Inbox placement tests
Analytics cover sends, replies, bounces and placement tests, and the dashboard shows a health score for each connected mailbox.
- 8
A 2.2 GPA, above 23 of 61
That is against the other email verification and deliverability tools we grade, on value, the free plan, features, ease of use and platforms.
- 9
Keep it
To replace Warmbly you would be making a network of real inboxes that open and answer your emails. That is not a weekend's work, with an AI app builder or without one.
Warmbly at a glance
- Pricing
- Free trial, from $23 per month, billed yearly ($29 billed monthly)
- Free plan
- No
- Free trial
- 14-day free trial, no credit card
- Runs on
- Web
- Made by
- Warmbly
- Category
- Email Verification & Deliverability
- Our grade
- 2.2 GPA, fair
The report card
Best for cold email sending with mailbox warmup in one place
Warmbly bundles mailbox warmup, cold campaigns, a shared inbox and placement tests, and the code is open source. Plans are capped by cold emails a day, and the CRM, API and team roles all sit on the dearer tiers.
| Subject | Grade | Comment |
|---|---|---|
| Value for money | C | Starter is $23 a month billed yearly ($29 monthly), which is the category's middle figure. It covers 150 cold emails a day. |
| Free plan and trial | C | 14-day trial with no card. There is no free plan. |
| Features | C | Warmup, campaigns, unified inbox, placement tests, CRM and lead finder. The CRM and API need Grow ($71), and each mailbox defaults to 50 sends a day. |
| Ease of use | C | No rating on record. You connect mailboxes, set up warmup and build campaigns, and self-hosting is an option. |
| Platforms and integrations | B | Web app with four listed integrations, an API and webhooks from Grow. No desktop or phone app. |
An A is worth 4 points, a B 3, a C 2, a D 1 and an F nothing. The GPA is the average of the five.
Who Warmbly is for
- Fits if you send cold email from several mailboxes and want warmup built in
- Works for teams happy to self-host and read the source
Who it is not for
- Skip it if you want a free plan, as there is only a 14-day trial
- Tight if you send in volume, since Starter stops at 150 cold emails a day
- Pricey if you need roles and an audit log, which start at Business, $263 a month
- Watch out: self-hosted warmup only uses the mailboxes you connect, not the shared pool
- Watch out: Agency plans pool sends across clients, and top-up packs cost extra
Good to know
Good for
- Teams sending cold email from many mailboxes
- Agencies running outreach for several clients
- Teams that want to host their own cold email stack
Worth knowing
- Plans are capped by cold emails a day, with each mailbox limited to 50 a day by default.
- The CRM and API need Grow or above, and team roles and audit log need Business.
- Self-hosted warmup uses only the mailboxes you connect, not the cloud's shared pool.
- Agency plans pool sends across clients; top-up packs of 50,000 sends cost $85 (Agency) or $60 (Agency Pro).
Part 02 · Pricing
What it costs
Every plan, the free plan, ways to pay less and how prices have moved
$23
A month to start
Warmbly is a paid product with a free trial, starting at $23 per month, billed yearly ($29 billed monthly).
Starter
$23
per month, billed yearly ($29 billed monthly)
150 cold emails a day, up to 4,500 a month; unlimited mailboxes and warmup, community support.
Grow
$71
per month, billed yearly ($89 billed monthly)
3,000 cold emails a day, up to 90,000 a month; adds CRM, API and webhooks, email support.
Business
$263
per month, billed yearly ($329 billed monthly)
15,000 cold emails a day, up to 450,000 a month; team roles, audit log, priority support.
Agency
$199
per month, billed yearly ($249 billed monthly)
150,000 sends a month shared by unlimited clients, with a white-label portal and $10 of shared AI.
Agency Pro
$479
per month for 500,000 sends, billed yearly ($599 billed monthly)
Full white-label; 500,000 sends a month shared by every client, $30 of shared AI.
Enterprise
Custom
Over 15,000 cold emails a day, custom contract and dedicated support; sold through sales.
Trying it first
14-day free trial, no credit card
Read from warmbly.com on Nov 13, 2026.
Ways to pay less
Annual discount
20% off yearly billing
The pricing page shows a Save 20% toggle for yearly billing, for example Starter at $23 instead of $29 a month.
Stated on warmbly.com
Part 03 · Features
What it does
Its main features, where it runs, what it works with and who makes it
1
Place it runs: Web
Open-source cold email platform with mailbox warmup. Here is what it does, as its own site describes it, and what it covers: open source, self-hostable, public API, workflow automation, inbox warm-up.
Warmup, campaigns, unified inbox, placement tests, CRM and lead finder.
- Mailbox warmup
- Warmup is unlimited on every paid plan and runs in a shared premium pool, ramping each mailbox's daily volume over time.
- Campaigns and unified inbox
- Sequences with follow-ups, branching and A/B tests send across mailboxes, and every reply lands in one inbox with labels.
- Inbox placement tests
- Analytics cover sends, replies, bounces and placement tests, and the dashboard shows a health score for each connected mailbox.
- CRM, lead finder and automations
- A built-in CRM tracks deals and tasks, a lead finder searches OpenStreetMap, and automations act when a reply arrives.
- Self-hosting
- The platform is Apache 2.0 licensed and can run on your own server, where warmup uses only the mailboxes you connect.
Where it runs
- Web
What it works with
- Google Workspace
- Microsoft 365
- Slack
- SMTP / IMAP
Warmbly is made by Warmbly.
Part 04 · Standing
Where it stands
Its grades against its category, and whether to keep it or make your own
23/61
Other email verification and deliverability tools it is graded above
Warmbly's GPA of 2.2 is higher than 23 of the 61 other email verification and deliverability tools we grade, and level with 13.
It stands best on platforms and integrations (B, above 28 of 61) and worst on features (C, above 0).
Its paid plans start at $23 a month, against a middle price of $21.50 for the category: 23 of the 43 others that charge start lower.
On features, ease of use and platforms it scores 2.3 out of 4. 7 tools score higher and cost less.
Each grade against the category
Every bar is all 62 email verification and deliverability tools we grade, cut by the letter each got. Warmbly’s own letter is outlined.
- CValue for moneyAbove 9 of 61
- CFree plan and trialAbove 9 of 61
- CFeaturesAbove 0 of 61
- CEase of useAbove 2 of 61
- BPlatforms and integrationsAbove 28 of 61
Price against what you get
Each dot is one of 45 email verification and deliverability tools. Further left costs less; higher up scores better on features, ease of use and platforms. Warmbly is the marked dot.
What paid plans start at, a month (each step along is roughly double) →
Keep it, or make your own?
Whether this is something you could build for yourself with an AI app builder, and what you would give up.
Keep it
To replace Warmbly you would be making a network of real inboxes that open and answer your emails. That is not a weekend's work, with an AI app builder or without one.
It costs $276 a year. Warmbly is open source, so there is a third way: take its code and run it yourself.
What you could not
- A network of real inboxes that open and answer your emails.
- Connections to other products, each kept working as those products change.
What this rests on. Warmbly’s listing: what it does, where it runs, what it plugs into and what it costs. It is a judgement about the kind of software this is. We have not built a replacement for it, and making your own means looking after it too. How we decide, and every tool’s verdict.
Part 05 · Alternatives
The alternatives
The tools it is most often weighed against, side by side
Warmup Inbox, MailReach, Warmy, InboxAlly and Mailwarm
The 5 tools Warmbly is most often weighed against, with where each one differs from it.
- 2.4GPA
Warmup Inbox
Free trial · from $15/mo
Email warm-up through a network of real inboxes, priced per inbox.
- Warmbly is open source and self-hostable, according to its own site.
- Warmbly also covers workflow automation.
- Warmup Inbox also covers email campaigns.
- 1.8GPA
MailReach
From $20/mo
Email warm-up and inbox placement tests, priced per mailbox.
- Warmbly is open source and self-hostable, according to its own site.
- Warmbly also covers workflow automation.
- 2.4GPA
Warmy
Free trial · from $49/mo
Email warm-up with seed testing, verification and DMARC monitoring.
- Only Warmy lists a browser extension.
- Warmbly is open source and self-hostable, according to its own site.
- Warmbly also covers workflow automation.
- 2.0GPA
InboxAlly
Free trial · from $149/mo
Email warm-up and reputation repair through a network of seed inboxes.
- Warmbly is open source and self-hostable, according to its own site.
- Warmbly also covers workflow automation.
- 1.6GPA
Mailwarm
From $69/mo
Email warmup service with deliverability guidance.
- Warmbly is open source and self-hostable, according to its own site.
- Warmbly also covers workflow automation.
- Mailwarm also covers reports.
Part 06 · Questions
Quick answers
The questions people ask about it, each answered in a line or two
14
Questions, each answered in a line or two
The short version of everything above, for when you only need the answer. Each one is told in full in its part of the guide.
Is Warmbly free?
No, Warmbly is a paid product, but you can try it first. 14-day free trial, no credit card.
How much does Warmbly cost?
Warmbly lists 6 plans. Starter: $23 per month, billed yearly ($29 billed monthly).
What platforms does Warmbly work on?
Warmbly is available on Web.
Does Warmbly offer any discounts?
Warmbly publicly lists the following: 20% off yearly billing.
Does Warmbly have an Android app?
No Android app was listed when its pages were read on Nov 13, 2026. Warmbly is listed for Web.
Does Warmbly have an iPhone app?
No iPhone app was listed when its pages were read on Nov 13, 2026. Warmbly is listed for Web.
Is Warmbly open source?
Yes. Warmbly is open source, according to its own site.
Does Warmbly have an API?
Yes. Warmbly offers a public API, according to its own site.
What does Warmbly integrate with?
Warmbly's listing names Google Workspace, Microsoft 365, Slack and SMTP / IMAP.
Who makes Warmbly?
Warmbly is made by a company of the same name.
What are the alternatives to Warmbly?
The closest alternatives to Warmbly in our directory are Warmup Inbox, MailReach, Warmy, InboxAlly and Mailwarm.
How does Warmbly compare with other email verification and deliverability tools?
Warmbly's GPA of 2.2 is higher than 23 of the 61 other email verification and deliverability tools we grade, and level with 13.
Is Warmbly good value for money?
ToolGPA grades Warmbly C for value for money. Its paid plans start at $23 a month, against a middle price of $21.50 for the category: 23 of the 43 others that charge start lower.
Could I make my own version of Warmbly?
To replace Warmbly you would be making a network of real inboxes that open and answer your emails.
Where this guide comes from
The prices, plans, platforms and features were read from Warmbly’s own pages on Nov 13, 2026, and the grades were given on Nov 13, 2026. Graded from this listing, whose facts were read from Warmbly's own pages on 13 November 2026. Not based on using the product, and shorter than our full reviews.
Every tool we list gets five grades, A to F, each with its reason, and a GPA that averages them. How each is decided is at toolgpa.com/grades. This guide is ToolGPA’s own work; it is not made, paid for or approved by Warmbly. Prices change, so check warmbly.com before you buy.
Part 07 · About
About ToolGPA
Who made this guide, what else is on the site, and how to cite it
7,721
Tools graded, in 95 categories
ToolGPA grades software the way a school report grades a pupil: five subjects, a letter for each with the reason written beside it, and a GPA that averages them. Prices, plans and platforms are read from each maker’s own pages and dated, so you always know how fresh a figure is.
Every grade, review and ranking on ToolGPA is our own judgement. No company can pay for a grade or change one. Every tool on the site has a guide like this one, free to download and pass on. It all lives at toolgpa.com.
7,721
tools graded
95
categories
739
price changes on record
579
apps priced in 12 countries
What else is on toolgpa.com
- Warmbly, kept up to dateEverything in this guide, with prices and grades as they are todaytoolgpa.com/tools/warmbly
- How grades are givenThe rules behind every letter and every GPAtoolgpa.com/grades
- Value chartsWhat each tool costs against what it scores, for every categorytoolgpa.com/charts
- CompareAny two tools side by side, plan by plantoolgpa.com/compare
- Price changesEvery price rise and cut on record, each with its sourcetoolgpa.com/price-changes
- Prices by countryWhat apps cost on the App Store in 12 countriestoolgpa.com/prices-by-country
- Pay lessEvery public discount: yearly billing, students, nonprofitstoolgpa.com/save
- Keep or makeWhich tools are worth paying for, and which you could build yourselftoolgpa.com/keep-or-make
Scan for the live page
Prices and grades as they are today
Quoting this guide?
Please name ToolGPA and link to the live page, so readers can check the figures for themselves:
ToolGPA, "Warmbly: The Insider's Guide", checked Nov 13, 2026. https://toolgpa.com/tools/warmbly
Know someone choosing between email verification and deliverability tools?
Send them this guide: toolgpa.com/tools/warmbly/guide
ToolGPA elsewhere: youtube.com/@toolgpa
See our other guides
The best-graded email verification and deliverability tools after Warmbly, each with an Insider's Guide of its own.
- Email Verification & Deliverability Insider's GuideEvery one of the 63 email verification and deliverability tools we grade, compared
- QuickEmailVerification Insider's GuideBulk email list cleaning and a real-time verification API3.0 GPA
- Mail-Tester Insider's GuideSend an email to a test address and get a spam score out of 102.8 GPA
- Reoon Email Verifier Insider's GuideBulk and real-time email verification with refunds on unknowns2.8 GPA
Choosing software? Every tool graded, every price dated.
Compare tools at toolgpa.com ›Everything in this guide is ToolGPA’s own summary of what Warmbly’s pages, its app-store listings and public reviews said on the dates shown. Grades are our judgement under the rules at toolgpa.com/grades. Every grade, review and ranking on ToolGPA is our own judgement. No company can pay for a grade or change one. Warmbly is a trademark of its owner, and this guide is not made, paid for or approved by Warmbly. Prices and plans change: check warmbly.com before you buy.