Abstract API vs Mailboxlayer
Both are validation APIs priced by monthly request quota. Mailboxlayer's Basic plan is $14.99 a month for 5,000 requests. Abstract API's Starter plan is $19 a month for 5,000 requests billed monthly, or $17 a month billed yearly. Mailboxlayer's ladder reaches 250,000 requests for $249.99; Abstract's Starter reaches 150,000 a month for $199. Abstract suits teams already using its other APIs.
Prices read from abstractapi.com and mailboxlayer.com. We sell a competing product, and it is not in the verdict above — where we fit is at the bottom.
| Abstract API | Mailboxlayer | |
|---|---|---|
| Cheapest route | $19/mo | $14.99/mo |
| Per year, if subscribed | $204 | $161.99 |
| Metering | Monthly request allowance | Monthly API request quota |
| Credits expire | Allowance resets monthly | Allowance resets monthly |
| Product type | Validation API | Validation API |
| Price checked | 2026-10-12 | 2026-10-12 |
Cost for one pass over a list
Each vendor’s cheapest available route. An empty cell means that vendor does not publish an allowance we can calculate from, not that it is free.
| List size | Abstract API | Mailboxlayer | Cheaper |
|---|---|---|---|
| 1,000 | $19.00 | $14.99 | Mailboxlayer |
| 10,000 | $38.00 | $29.98 | Mailboxlayer |
| 50,000 | $99.00 | $74.99 | Mailboxlayer |
| 100,000 | $198.00 | $149.98 | Mailboxlayer |
| 1,000,000 | $1393.00 | $999.96 | Mailboxlayer |
Cost at a steady monthly volume
What the same volume costs every month, on each vendor’s cheapest route that covers it in one month: a subscription tier whose allowance fits, or buying the covering pack again.
| Per month | Abstract API | Mailboxlayer |
|---|---|---|
| 10,000 | $39.00$39/mo plan with 15,000 a month | $74.99$74.99/mo plan with 50,000 a month |
| 50,000 | $99.00$99/mo plan with 50,000 a month | $74.99$74.99/mo plan with 50,000 a month |
| 100,000 | $199.00$199/mo plan with 150,000 a month | $249.99$249.99/mo plan with 250,000 a month |
| 1,000,000 | —No published plan covers this volume | —No published plan covers this volume |
How each one bills you
Abstract API charges $19 a month for 5,000 verifications, or $204 for a year, metered as monthly request allowance. Mailboxlayer charges $14.99 a month for 5,000 verifications, or $161.99 for a year, metered as monthly api request quota.
Abstract API's allowance is tied to the subscription period. Mailboxlayer's allowance is tied to the subscription period. For uneven volume, expiry often matters more than the headline price, because credits that lapse raise the real cost of every address you did verify.
What to watch with Abstract API: the plan is a request quota, so a bulk clean and your live sign-up checks compete for the same allowance. With Mailboxlayer: it is an API quota, not a list tool, so cleaning a CSV means writing the batching yourself and every row counts against the month.
Both meter verifications, so checking the same list again costs again. Before committing to either, verify an address you invented at a real domain and an address at a catch-all domain on both. The first should come back invalid and the second as risky or accept-all, not valid.
Choose Abstract API if
you already use Abstract's other APIs and want one key and one bill.
Disclosure — our product
Where SimpleVerifier fits, and where it does not
We publish this comparison and we sell a third option, so treat the rest of this section as the pitch it is. SimpleVerifier is a monthly price with no per-email fees: verification is never cut off (each plan sets how many a month run at full speed) and API calls are included each month, so there are no credits to buy or expire:
Pro $39/mo
Email verification with the first 100,000 checks a month at full speed, then slower, never cut off, plus the finder and the API.
Pro + Phone $49.99/mo
Pro with the phone add-on: live carrier lookups for your phone lists.
Business $99/mo
For senders with big lists: the first 300,000 checks a month at full speed, then slower, never cut off.
Agency $249/mo
For agencies running lists for clients: the first 750,000 checks a month at full speed, then slower, never cut off.
That is worth it in two cases: large lists, because volume does not change the price, and lists you verify repeatedly, because a confirmed result is cached for 14 days so the second pass costs nothing. Outside those two cases, a metered vendor is usually cheaper and you should use one, Abstract API and Mailboxlayer included.
Run the same test on any verifier
Type any address. It gets the same check the paid plans run: syntax, the domain’s mail servers and, where the provider allows it, a live mailbox check. Nothing is sent to the address.
Five checks a minute, no account needed. Nothing is sent to the address — we ask its mail server whether the mailbox exists, then disconnect.
Have a list? Sign in with Google and the first 100 addresses are checked free, with results to download. No card.
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Common questions
- Abstract API or Mailboxlayer — which is better?
- Both are validation APIs priced by monthly request quota. Mailboxlayer's Basic plan is $14.99 a month for 5,000 requests. Abstract API's Starter plan is $19 a month for 5,000 requests billed monthly, or $17 a month billed yearly. Mailboxlayer's ladder reaches 250,000 requests for $249.99; Abstract's Starter reaches 150,000 a month for $199. Abstract suits teams already using its other APIs.
- How much do Abstract API and Mailboxlayer cost?
- Abstract API costs $19 a month for 5,000 verifications, or $204 for a year. Mailboxlayer costs $14.99 a month for 5,000 verifications, or $161.99 for a year. Both read from their own pricing pages — Abstract API on 2026-10-12, Mailboxlayer on 2026-10-12.
- Should I choose Abstract API?
- Choose Abstract API if you already use Abstract's other APIs and want one key and one bill.
- Should I choose Mailboxlayer?
- Choose Mailboxlayer if you want published request quotas at each price tier.
- Is there an alternative to both Abstract API and Mailboxlayer?
- SimpleVerifier is a monthly plan rather than credits: Pro at $39, Business at $99 or Agency at $249 a month. Email verification is never cut off (on Pro the first 100,000 a month run at full speed, more on Business and Agency), and API calls are included each month. It suits large lists and lists you re-check often. For a small one-off clean, a metered vendor such as Abstract API or Mailboxlayer can cost less.