Find bad addresses before they kill your reputation.
KillBounce checks every email — syntax, DNS, live mailbox probe — before you hit send. So bad addresses never get on the truck.
Plays nice with your stack
One bad list. Years of trust. Burned in a week.
Three vital signs. All from skipping verification on one send. Numbers below are typical for a 50K-person list with a 12% bounce rate.
Without verification — after 1 send
CRITICAL
0/100
Sender score
POOR
0%
Inbox placement
BLEEDING
$0
Wasted spend / month
With verification — every send
EXCELLENT
0/100
Sender score
HEALTHY
0%
Inbox placement
SAVED
$0
Wasted spend / month
The numbers above flip from red to green for $30 a month.
Less than what one bad send costs in lost ad spend.
0%
list decay per year
Source · HubSpot
0%
avg. bounce rate without verification
Source · Mailgun
0×
ROI on every clean email sent
Source · DMA
One bad send. 30 days of fallout.
Watch what happens to your sender reputation when you skip the verification step. Every line is anchored to actual ESP behaviour — not theory.
Sender score · last 30 days
Day 1
You hit send
12% of addresses bounce. The ESP starts taking notes. You don't feel it yet.
Skip the timeline. Verify first.
KillBounce catches the dead, the risky, and the traps in one pass — your reputation stays at 99+.
How it actually works
From CSV to clean list. Usually under a minute.
No setup. No SQL. No CSV gymnastics. Drop in a list, get a verified one back.
Drop in your list
01CSV, TXT, XLS, or paste. Up to 5M addresses per job. We dedupe before you even hit verify.
- Drag & drop or paste
- Auto-deduplicate
- 10+ formats
We run the gauntlet
02Each address passes three checks: syntax, DNS/MX, live mailbox probe. We catch what regex never could.
- Syntax + format
- MX & catch-all
- Live mailbox probe
Take the clean list
03Categorized results with a reason code per address. Export CSV, ping a webhook, or pipe straight to your ESP.
- CSV in one click
- Reason codes
- API + webhooks
What we promise
We're early. So we lead with promises, not vanity metrics.
No fake customer counts. No borrowed logos. Just the four things we hold ourselves to from day one.
Three-layer pipeline
Every address runs through syntax, DNS/MX, and a live SMTP probe. No regex theatre.
How the system is built — verifiable in our docs.
Refund on accuracy miss
If a verification turns out wrong, we return the credit. No support ticket, no debate.
Written into our terms.
No subscriptions, no expiry
Pay for credits when you need them. Use them whenever. They don't evaporate.
Pricing is public — no quote-required tiers.
Real humans on chat
Engineers, not a chatbot. We answer support in the same Slack we ship from.
You can email a founder right now.
Built different
Six things you'll notice in the first hour.
Concrete, not corporate. Each one survives a side-by-side with the household names.
Wrong-verdict refund
If we say "valid" and it bounces, the credit is back in your account. Automatic. No ticket.
Credit
Refunded
20% cheaper, same checks
Identical syntax / DNS / SMTP pipeline to NeverBounce, ZeroBounce, Mailgun. We just cost less.
Catch-all flagging
Domains that "accept anything" then silently drop mail are marked risky — not falsely passed as valid.
Encrypted, auto-deleted
AES-256 at rest, TLS 1.3 in flight. Lists purge after 24h by default. Zero-retention on request.
REST API + SDKs
Idempotent endpoints, OpenAPI spec, official SDKs for Python, Node, PHP, Ruby, Go.
Per-address dashboard
Drill into any verification, see which of the three layers failed, and export the slice to CSV.
Valid
8.2K
Risky
412
Invalid
184
For every team
Different teams. Same enemy: bounces.
Stop training Gmail to filter you
Every bounce nudges your sender score down. Clean the list before the campaign — keep the inbox door open.
What to expect
- Bulk list cleaning (up to 5M emails)
- Catch-all & disposable detection
- Spam-trap identification
- Native Mailchimp & HubSpot flows
Pre-send list hygiene
Your campaigns, fewer bounces
Developer experience
An API you'll actually enjoy.
Clean REST endpoints, typed SDKs, idempotent calls, and async webhooks for big jobs. Drop in, ship today.
~150ms median
Single-call latency
5 SDKs
Python, Node, PHP, Ruby, Go
Async webhooks
For batch jobs
import killbounce
client = killbounce.Client(api_key="...")
result = client.verify("test@example.com")
if result.status == "valid":
print(f"✓ Deliverable — score {result.score}")
else:
print(f"✗ {result.reason}")Pricing
Pay for what you check. Nothing else.
Slide to your list size. We'll do the math live — and tell you what the competition would charge.
You pay
$30.0
$0.0030 per email · one-time
ZeroBounce price
$40.0
$0.0040 per email · public rate
You save
$10.0
25% less than ZeroBounce
No card to start · 100 free credits · cancel by closing the tab
Or pick a popular size
Head to head
Pick who you're paying now. We'll show you the gap.
Public pricing from each vendor, this month. No asterisks, no “contact sales” tricks.
Compare against
Us
KillBounce
per 10,000 emails
- 99.9% accuracy
- 24/7 live support
- Bulk verification
- Real-time API
- 100 free credits to start
Them
ZeroBounce
per 10,000 emails
- 99.6% accuracy
- 24/7 support
- Bulk verification
- Real-time API
- 100 free credits to start
Switch from ZeroBounce
Save $10 per 10K · 25% off
Show full spec sheet ↓
| Feature | KillBounce | ZeroBounce | NeverBounce | Mailgun |
|---|---|---|---|---|
| 10,000 credits | $30 | $40 | $38 | $45 |
| Accuracy rate | 99.9% | 99.6% | 99% | 98% |
| Bulk verification | ||||
| Real-time API | ||||
| Support | 24/7 live | 24/7 | Email only | Business hrs |
| Free credits | 100 | 100 | 1,000 | 0 |
Your lists never leave the safe
Encrypted, audited, purged. Compliance is not the marketing — it's the build.
SOC 2
Type I, audit underway
AES-256
at rest · TLS 1.3 in flight
GDPR
DPA on signup
24h purge
Zero-retention on request
Last-mile questions
Anything else on your mind?
The questions buyers actually ask, grouped so you can jump to what matters.
Still have a question?
Real engineers reply, usually under 10 minutes during business hours.
Stop sending into the void.
Get 100 free credits. No credit card. Set up in under 2 minutes.