Sluice vs Instantly
Instantly is a cold email sending platform with warmup and a 450M+ contact database attached; lead credits start at $47 a month for 1,500 (as of October 2026). Sluice is a finder: it locates people where they showed a need, scores them 0 to 100 and drafts messages. Many teams would use Sluice to choose who and Instantly to send.
What Instantly is good at
Instantly is a sending machine first. It spreads campaigns across many inboxes, runs warmup so new domains build a reputation before they carry cold mail, and puts a 450M+ contact database next to the sender so a list can become a live campaign in one place. Its credit policy is fair: no verified email, no charge. If the bottleneck is getting thousands of emails delivered each week, Instantly solves a problem Sluice does not touch.
Use Instantly if: Pick Instantly if cold email is your main channel, you send hundreds or thousands of messages a day, you need warmup and inbox rotation, and you already know which titles and industries to target. Agencies running many client campaigns at volume are its natural buyers.
| Instantly | Sluice | |
|---|---|---|
| What it is | Cold email sender with a contact database | Lead finder and scorer that drafts messages |
| Entry price (as of October 2026) | Lead credits from $47/mo for 1,500 | $9/mo for 900 credits |
| Where leads come from | 450M+ contact database | Post engagers, reviewers, advertisers, hiring companies, local listings, visitors, directory |
| A lookup with no email | Not charged | Not charged |
| Why this person, now | Filters on title, company and industry | Score 0 to 100 with a link to what they said |
| Sending volume and warmup | Built for it | No warmup; sends only messages you approve |
| Proven at large volume | Yes, sending is its core | Not yet; new, no public reviews |
| Channels | Email, LinkedIn, Instagram, WhatsApp via accounts you connect ($10.80/mo each) |
Two tools that answer different questions
Instantly answers "how do I get these emails delivered?" Sluice answers "who should I be emailing, and what do I say to them?" The confusion comes from the fact that Instantly also sells contacts, and Sluice can also send. But the centre of gravity of each product is in a different place, and that decides which one you need.
If you already have a clear list of job titles and industries, a sending tool with a database attached is a reasonable shortcut. If your problem is that the list is cold and nobody replies, the issue is upstream of sending, and more volume makes it worse.
Where does each one get its leads?
Instantly's leads come from a contact database of more than 450 million people. You filter by title, seniority, location, company size, and pull the matches into a campaign. Everyone on the resulting list fits a description. None of them did anything recently that suggests they want what you sell.
Sluice starts from traces people leave in public. Some examples of what that looks like in practice:
- A Reddit thread where someone asks for a replacement for the tool you compete with. Everyone who replied with the same complaint becomes a lead. See finding leads on Reddit.
- A competitor's page on G2 with a run of two-star reviews. The reviewers become leads, with their stars and words beside them. See competitor reviews as leads.
- Companies hiring for the role your product helps, by place.
- Your own website's visitors, where the visiting company owns its network.
Each person is scored against your customer profile (fit from 0 to 100, worth approaching or not, and whether what they said suggests the problem is live now). 70 is the line for worth contacting. The link back to the source travels with them.
What does a lead cost on each?
Say you want 200 contacts with working emails.
| Instantly (own data) | Instantly (partner data) | Sluice directory | |
|---|---|---|---|
| Credits per email | 1 | 2 | 5 cents per reveal |
| 200 contacts | 200 of 1,500 monthly credits | 400 of 1,500 | $10 |
| Plan needed | Lead credits from $47/mo | Same | Starter $9/mo (900 credits) |
| What you get | Matches to your filters | Same | Only people who scored 70+ |
Per email, Instantly is cheaper once you use the whole allowance: $47 for 1,500 credits works out at about 3 cents each on its own data. Sluice costs more per contact but previews are free and only people who clear 70 are revealed, so you pay for the 200 who fit rather than 200 who match a title. Both skip the charge when no email is found. Sluice also refunds a bounced address exactly what it cost. More detail in what a lead actually costs.
Where Instantly is better
Sending. Warmup gets a new domain's reputation up before it carries cold mail. Spreading volume across many inboxes keeps any single one under the limits that trigger spam filtering. A team sending a few thousand emails a week needs that machinery, and Sluice does not have it.
Sluice sends only through accounts you connect (Gmail or Outlook for email, plus LinkedIn, Instagram and WhatsApp), each at $10.80 a month, and only messages you have approved one by one or as a sequence. That is deliberate. It suits someone sending 20 considered messages a day, not 2,000.
Where Sluice is better
- Choosing who. A score and a reason for every person, not a filter match.
- Writing the first line. Drafts come from the person's own words, and every draft, including yours, gets a score and a reason before it can be queued. See writing a first message from their words.
- Channels beyond email. Someone who commented on a LinkedIn post is often better reached on LinkedIn.
- Not pitching customers. With HubSpot connected, customers and open deals come back and are never cold-pitched.
Sluice is also new. There are no public customer logos or reviews yet, and it has not been proven at large volume. Instantly has.
How to use both
- Build a customer profile in Sluice and run two or three signal sources (a competitor's reviews, a subreddit, companies hiring for the role you sell to).
- Keep the people who scored 70 or above. Read the reason beside each.
- Move them into an Instantly campaign. There is no native integration, so this is manual today, or through HubSpot if your Instantly setup reads from it.
- Use the reason as the first line of each email, so the campaign opens with something the person actually said.
The decision
If your problem is delivery at volume, buy Instantly. If your problem is that nobody on the list cares, start with Sluice on the $9 plan and feed the people who clear 70 into whatever sender you already use.
Questions people ask
- Can Sluice replace Instantly?
- Not if you send cold email at volume. Sluice sends only messages you approve, through Gmail, Outlook, LinkedIn, Instagram or WhatsApp accounts you connect, and it has no warmup. Instantly is built for volume sending.
- Does Instantly charge when it finds no email?
- No. Instantly's help centre says no credit is charged when no verified email is found. Its own data costs 1 credit per lead and partner data costs 2.
- Can I use Sluice and Instantly together?
- Yes. Sluice decides who is worth contacting and why; Instantly sends the campaign. There is no native connection between them today, so the handoff is manual or through HubSpot if your sending tool already reads from it.
- Which is cheaper for a small list?
- For 100 well-chosen contacts, Sluice's directory reveals cost $5 at 5 cents each on top of a $9 plan. Instantly's 1,500 credits for $47 is cheaper per email if you need volume more than selection.
Sources
Try it on your own market
Sluice quotes the worst-case price before anything runs and charges only for lookups that found something, so finding out costs close to nothing.
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