
Instantly.ai
Warmly
SmartLead.ai
lemlist
Reply.io
Flat-rate email warmup from $19/month: 5 mailboxes on Starter, 25 on Growth, no per-inbox fees. Builds real sender reputation for Gmail and Outlook so cold outreach lands in the inbox, not spam.

imapsync
IMAP Upload
audriga Email and Groupware migration
CloudSponge
Layercode UseCSV
Cloudiway
MigrationWiz
ShuttleCloud is an API that allows developers to import address books from hundreds of email providers.
Which is more popular?
Website, pricing, platforms and company facts side by side.
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| Website | warmerly.com | shuttlecloud.com |
| Pricing | — | |
| Company | Startup from the United Kingdom · 1 - 9 employees · 2026 | — |
| Listed in |
In their own words, as submitted to SaaSHub.


Warmerly is an email warmup and deliverability platform for teams running cold outreach. It builds sender reputation on Gmail, Outlook and custom mailboxes by running continuous human-like warmup — threaded conversations with quoted replies, natural send delays, opens, stars and labels — against...
No description of ShuttleCloud yet.
What each product offers, as listed by its team.


Possible disadvantages
An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
No analysis of ShuttleCloud yet.
Walkthroughs and reviews on video.
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Prometheus Is Good for Your Small Startup by Ignacio P. Carretero, ShuttleCloud
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How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing Warmerly and ShuttleCloud.
Warmerly's answer
Built around agency workspaces, not a single sender identity Manages multiple client campaigns from one account without mixing contacts or messaging Multi-channel outreach across email and LinkedIn (via Unipile) in one workflow Built by an agency founder actively running outreach for real clients through Warmerly itself, not designed in the abstract
Warmerly's answer
Most outreach tools, including Instantly.ai and Warmly, are built for one person running their own outreach from one inbox. Agencies managing several client accounts get forced into workarounds: separate logins per client, or juggling multiple tools to keep campaigns from bleeding into each other. Warmerly is built specifically around that agency use case, with client workspaces as the default structure rather than something bolted on later.
Warmerly's answer
Small agencies running outreach campaigns on behalf of multiple clients, particularly agencies doing lead generation or business development work where they need to manage separate campaigns, contacts, and messaging for each client from one place.
Warmerly's answer
Warmerly started as an email warmup and deliverability tool, competing directly with Instantly.ai. While running it alongside Octelis, a Birmingham based digital marketing agency, the founder kept hitting the same problem from the inside: agencies running outreach for multiple clients need a way to separate campaigns cleanly, and existing tools weren't built for that. That reshaped Warmerly into a multi-channel outreach platform built around agency workspaces instead of a single sender.
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