Email verification API pricing looks simple until you try to compare it. One vendor sells credit packs, another sells a monthly plan, a third has a calculator with a dozen tiers, and the fine print on credit expiry changes the real cost more than the headline rate. If you're budgeting for an API that checks every signup — or a bulk email verifier for quarterly list cleaning — you need a cost per 1,000 you can trust.
This post puts six providers side by side at four volumes (5,000, 10,000, 100,000 and 500,000 emails), lists the costs that don't show up on the pricing page, and works through a full-year example for a SaaS app validating 20,000 signups a month. Every number comes from public pricing, and the arithmetic is shown.
$0.60 per 1,000 emails is InboxVet's lowest rate (Enterprise, $300 for 500,000 credits that never expire).
Figure: The three ways verification is packaged — pay-as-you-go credit packs, monthly subscriptions and volume calculators — and the catch to check with each.
How Email Verification API Pricing Works
Almost every provider bills per email checked, but they package it in three ways:
· Pay-as-you-go credit packs. Buy a block of credits once and spend them via API or bulk upload. Larger packs cost less per 1,000. The catch to check is expiry.
· Monthly subscriptions. A fixed fee includes a monthly allowance, often bundled with deliverability tools. Good if your volume is steady; wasteful if it isn't.
· Volume calculators. A sliding per-email rate that drops as you buy more. Useful at very high volume, but harder to compare without plugging in your exact number.
The unit is nearly always the same: one credit per email checked. On InboxVet, one credit covers one verification whether the result is VALID, INVALID or RISKY, and the same price applies to the real-time API, the batch endpoint and dashboard CSV uploads.
Email Verification API Pricing at Four Volumes
The table shows the cheapest published way to buy each volume. Where a provider doesn't list a tier in the figures we have, we say so rather than guess.
Competitor prices checked from public pricing pages in early October 2026 — confirm on the vendor's site before buying.
| Provider | 5,000 | 10,000 | 100,000 | 500,000 | Credit expiry |
|---|---|---|---|---|---|
| InboxVet | $25 | $50 (2 × Starter) | $125 (Scale, 125,000 credits) | $300 (Enterprise) | Never |
| ZeroBounce | $69 | $129 | $649 | Not in our data (1,000,000 ≈ $3,199) | Depends on account creation date — check current terms |
| NeverBounce | $40 | $80, or $49/mo Growth plan | Volume tier — use calculator | Volume tier — use calculator | 12 months (pay-as-you-go) |
| Kickbox | $40 | $70 | $500 | $2,500 (5 × 100,000; ask about larger) | 12 months |
| Bouncer | $35 | $60 | $400 | Not in our data | Never |
| MillionVerifier | Not in our data (smallest tier we have is 10,000) | ~$37–39 | ~$178 (2 × 50,000 at ~$89) | Not in our data (1,000,000 ≈ $449) | Never |
Now the same numbers as cost per 1,000 (price ÷ thousands of emails):
| Provider | 5,000 | 10,000 | 100,000 | 500,000 |
|---|---|---|---|---|
| InboxVet | $5.00 | $5.00 | $1.00 per credit ($1.25 per 1,000 if you use only 100,000) | $0.60 |
| ZeroBounce | $13.80 | $12.90 | $6.49 | — ($3.20 at 1,000,000) |
| NeverBounce | $8.00 | $8.00 ($4.90 on Growth if all 10,000 are used) | Below $8.00 | Lower still; ~$2.00 at very high volume |
| Kickbox | $8.00 | $7.00 | $5.00 | $5.00 |
| Bouncer | $7.00 | $6.00 | $4.00 | — |
| MillionVerifier | — | ~$3.70–3.90 | ~$1.78 | — (~$0.45 at 1,000,000) |
What the tables say, plainly:
· Small volumes (5,000–10,000): InboxVet is lowest at 5,000 among providers with a 5,000 tier in our data. At 10,000, MillionVerifier is cheapest, and NeverBounce's Growth plan is competitive if you use the full allowance every month.
· Mid volumes (100,000): InboxVet's Scale pack ($125) is the lowest published figure we found, ahead of two MillionVerifier 50,000 packs (~$178). Bouncer ($400), Kickbox ($500) and ZeroBounce ($649) are several times higher.
· Very high volumes (1,000,000): MillionVerifier wins at about $449, versus $600 for two InboxVet Enterprise packs.
Emailable, which we didn't include in the tables, prices roughly $38–50 per 5,000 ($7.60–10.00 per 1,000) and gives 250 free credits.
Figure: Cheapest published cost per 1,000 emails at each volume (log scale). MillionVerifier is lowest at 10,000 and 1,000,000; InboxVet is lowest at 100,000.
Hidden Costs in Email Verification API Pricing
1. Credit Expiry
This is the biggest one. NeverBounce pay-as-you-go credits and Kickbox credits expire 12 months after purchase. ZeroBounce credits never expire for accounts created on or before June 1, 2026; newer accounts' purchased credits are valid for at least two years. InboxVet, Bouncer and MillionVerifier credits don't expire.
Expiry turns a per-1,000 rate into a bet on your future volume. Buy 100,000 Kickbox credits for $500 and use 60,000 before they lapse, and you've paid $8.33 per 1,000 used, not $5.00. With email verification credits that never expire, a big pack is a discount with no downside.
2. Minimum Purchases
ZeroBounce's smallest pay-as-you-go purchase is 2,000 credits for $39 — $19.50 per 1,000. Fine for testing, expensive as a habit. InboxVet's smallest pack is 5,000 for $25.
3. Subscriptions You Don't Fully Use
A monthly plan's effective rate assumes you use the whole allowance. NeverBounce Growth is $4.90 per 1,000 at 10,000 emails a month, but $9.80 per 1,000 in a month you only verify 5,000. Subscriptions also keep billing when you pause campaigns. Pay as you go email verification avoids that: InboxVet has no subscription, no auto-renewal and no auto-charge when credits run out — the API simply returns an insufficient-credits error.
4. How Unknown Results Are Billed
Some addresses can't be resolved conclusively — a mail server times out, or a catch-all domain accepts everything. Check whether unknown results are charged on each provider you're considering, because it changes the real cost on B2B lists. On InboxVet, every verification costs one credit regardless of result, so the price is predictable.
5. Add-Ons Billed Separately
Real-time form protection, deliverability monitoring and scoring are sometimes separate products. Bouncer Shield, for example, is billed separately from list verification. ZeroBounce ONE bundles credits with deliverability tools from $99/mo ($79/mo billed annually), including 10,000 credits. InboxVet's Complete bundle is $39/mo for 10,000 validation credits a month plus DMARC reporting for 10 domains, 50 blacklist monitors, 12-month history, API access and webhook/Slack alerts.
Worked Example: A SaaS Validating 20,000 Signups a Month
Say you run a SaaS app that checks every new signup in real time: 20,000 verifications a month, or 240,000 a year. Here's how email verification API pricing plays out over a year at each provider's best-fitting published tier, calculated as 240 × rate per 1,000:
| Option | How you'd buy | Rate per 1,000 | Effective annual cost |
|---|---|---|---|
| InboxVet Enterprise | One $300 pack (500,000 credits lasts 25 months) | $0.60 | $144 |
| InboxVet Scale | Two $125 packs (250,000 credits; 10,000 carry over) | $1.00 | $240 ($250 cash) |
| InboxVet Complete + Scale | $39/mo × 12 (120,000 credits) + one Scale pack (125,000) | — | $593, including deliverability monitoring |
| MillionVerifier | 50,000 packs at ~$89 | ~$1.78 | ~$427 |
| MillionVerifier (1M pack) | One ~$449 pack (lasts ~50 months) | ~$0.45 | ~$108 |
| Bouncer | 100,000 packs at $400 | $4.00 | $960 |
| Kickbox | 100,000 packs at $500, bought as needed | $5.00 | $1,200 |
| ZeroBounce | 100,000 packs at $649 | $6.49 | $1,557.60 |
| NeverBounce | Pay-as-you-go at list rate | $8.00 (volume tiers lower) | Up to $1,920 — check calculator |
The honest read: if you're willing to prepay roughly $449 for four years of volume, MillionVerifier's million-credit pack has the lowest annualised cost. Weigh that against its focus — it's built for budget bulk cleaning, and the real-time API is less central to the product, which matters when the use case is live signups. InboxVet's Enterprise pack is the next lowest at $144 a year, with a sub-100ms average response for real-time checks. Bouncer, Kickbox, ZeroBounce and NeverBounce cost several times more at this volume, though ZeroBounce and NeverBounce bring broader suites and CRM integrations that some teams will happily pay for.
Expiry check: NeverBounce's Growth plan ($49/mo for up to 10,000) covers only half of this app's volume. And on Kickbox or NeverBounce pay-as-you-go, never buy more than 12 months of credits at once.
Figure: Effective annual cost of verifying 20,000 signups a month (240,000 a year) at each provider's best-fitting published tier, lowest to highest.
How to Run a Cheap Email Verification API Without Cutting Corners
The cheapest verification is the one you don't need to repeat. A few habits cut the bill regardless of provider:
· Verify once at capture. Check addresses at signup and store the result. Don't re-verify on every login.
· Deduplicate before bulk jobs. Lowercase and dedupe your CSV first — duplicates cost credits too.
· Re-verify on a schedule, not constantly. Lists decay steadily — commonly estimated at around 20–25% a year — so a quarterly or pre-campaign clean is usually enough for older contacts.
· Use the batch endpoint for backfills. InboxVet's batch API takes up to 1,000 emails per request, which keeps large jobs efficient.
· Size packs to your real annual volume. With non-expiring credits, buying a bigger tier early is a straight discount.
💡 Developer Tip: Every InboxVet response includes creditsRemaining. Log it and alert when it drops below about two weeks of usage, so you top up before signups start hitting the insufficient-credits error.
For bigger jobs, our guide to bulk email verification at 100k+ scale covers chunking and throughput, and email validation best practices covers when to verify. Request and response details are in the InboxVet API docs.
Which Pricing Model Fits You?
· Steady volume plus deliverability needs: a bundle such as InboxVet Complete ($39/mo) or ZeroBounce ONE ($99/mo).
· Spiky or seasonal volume: non-expiring pay-as-you-go packs.
· Huge one-off cleans: MillionVerifier for pure bulk price; InboxVet Enterprise if you also need a real-time API.
· Deep CRM workflows: NeverBounce or ZeroBounce, accepting the higher rate.
Full tier details are on the InboxVet pricing page.
Figure: Illustrative credit dashboard — a 500,000-credit Enterprise pack lasts 25 months at 20,000 signups a month, with an alert set at about two weeks of usage.
Frequently Asked Questions (FAQ)
Q: What is typical email verification API pricing per 1,000 emails?
A: On the published prices we compared, it ranges from about $0.45 per 1,000 (MillionVerifier at 1,000,000) to $13.80 per 1,000 (ZeroBounce at 5,000). Many land in the $4–8 per 1,000 range at 10,000–100,000 emails.
Q: What's the cheapest email verification API?
A: For very large bulk jobs, MillionVerifier. At 100,000 emails, InboxVet's Scale pack ($125 for 125,000) was the lowest published figure we found. If real-time API performance matters, compare response times on a free tier too.
Q: Do InboxVet credits expire?
A: No. Credits never expire, there's no subscription, and there's no auto-renewal or auto-charge when you run out.
Q: Is real-time API verification priced differently from bulk?
A: Not on InboxVet — single API calls, batch requests and CSV uploads all use one credit per email. Other providers may package real-time protection separately, as with Bouncer Shield.
Q: Am I charged for invalid or risky results?
A: On InboxVet, yes — one credit per verification regardless of result. Check whether unknown results are charged on any other provider you're evaluating.
Q: Is a subscription or pay-as-you-go better?
A: Subscriptions suit steady monthly volume, especially if you want bundled deliverability tools. Pay-as-you-go with non-expiring credits suits irregular or growing volume, because you never pay for unused allowance.
Pick the Price That Matches Your Volume
In email verification API pricing, the headline rate matters less than the fit: your annual volume, how steady it is, and whether credits will still be there when you need them. Work out your yearly count, compare effective cost per 1,000 used, and factor in expiry. For most API-first teams between 100,000 and 500,000 verifications a year, InboxVet's non-expiring packs land at $0.60–1.00 per 1,000.
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