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IsValid.dev VS mailboxlayer API

Compare IsValid.dev VS mailboxlayer API and see what are their differences

IsValid.dev

A powerful REST API for validating emails, IBANs, BIC/SWIFT codes, LEI, ISIN, credit cards, VAT numbers, phone numbers, and 70+ more validators. Free tier available.

Rating
0 reviews
Pricing
Freemium Free trial €9 / Monthly (10000 API calls / day)
Alternatives Is it good?
mailboxlayer API

Mailboxlayer is a free, simple and powerful JSON API offering instant email address validation & verification via syntax checks, typo and spelling checks, SMTP checks, free and disposable provider filtering, and much more.

Rating
0 reviews
Alternatives Is it good?
Modelence
Create production-ready applications with zero code sponsored
Note: These products don't have any matching categories. If you think this is a mistake, please edit the details of one of the products and suggest appropriate categories.

Which is more popular?

Based on our record, mailboxlayer API seems to be more popular. It has been mentioned 5 times since March 2021.

social mentions
0 vs 5
APIs popularity
100% vs 0%
alternatives listed
11 vs 60

Base details

Website, pricing, platforms and company facts side by side.

IsValid.dev
mailboxlayer API
Website isvalid.dev mailboxlayer.com
Pricing
Freemium Free trial €9 / Monthly (10000 API calls / day) Official pricing
Official pricing
Platforms
Python Node JS Wordpress
—
Listed in
API Tools Developer Tools Data Validation Credit Card Validator Email Validator Email Validation Phone Number Validation Developer APIs APIs API +7
Email Address Verification Email Marketing Email Verification Email Verification API +1

About IsValid.dev and mailboxlayer API

In their own words, as submitted to SaaSHub.

IsValid.dev
mailboxlayer API

IsValid is a validation API service for developers who need to quickly verify data formats without building their own validators. It offers 40+ endpoints covering financial identifiers (IBAN, BIC, ISIN, CUSIP), international standards (ISBN, ISSN), technology formats (UUID, JWT, QR codes),...

Read more about IsValid.dev

No description of mailboxlayer API yet.

Features and specs

What each product offers, as listed by its team.

IsValid.dev 5 features
mailboxlayer API 6 features
  • Lightweight schema validation
    IsValid.dev offers a minimal, lightweight approach to schema validation for TypeScript, avoiding the bloat that can come with larger validation libraries.
  • TypeScript-first design
    Built with TypeScript in mind, providing strong type inference so validated data automatically gets proper TypeScript types without extra manual typing.
  • Simple API
    The library offers an intuitive and easy-to-learn API for defining and running validations, making it accessible for developers to quickly get started.
  • Zero or minimal dependencies
    Being a lightweight tool, it typically has little to no external dependencies, reducing bundle size and potential security/maintenance issues from third-party packages.
  • Good for small to medium projects
    Its simplicity makes it well suited for smaller projects or use cases where heavier libraries like Zod or Yup might be overkill.

Possible disadvantages

  • Smaller community and ecosystem
    Compared to established validation libraries like Zod, Joi, or Yup, IsValid.dev has a much smaller user base, meaning fewer community resources, tutorials, and third-party integrations.
  • Limited documentation
    As a newer or less mainstream tool, its documentation may be less comprehensive than more established alternatives, making it harder to find answers to edge-case questions.
  • Fewer advanced features
    It may lack some of the advanced features found in more mature libraries, such as extensive built-in validators, custom error message localization, or complex schema composition tools.
  • Less battle-tested
    Being less widely adopted, it may not have been tested against as many real-world edge cases as more popular libraries, potentially leading to undiscovered bugs.
  • Uncertain long-term support
    Newer or niche libraries carry a higher risk of reduced maintenance or discontinuation over time compared to well-funded or widely-adopted projects.
  • Ease of Use
    Mailboxlayer API provides a simple interface that enables effortless integration into applications, allowing developers to validate and verify email addresses with minimal setup.
  • Real-time Email Validation
    The API offers real-time email address validation and verification, which helps in maintaining clean and accurate email lists.
  • Multi-format Support
    Mailboxlayer supports the validation of email addresses in multiple formats, making it versatile for different use cases.
  • Comprehensive Documentation
    Mailboxlayer provides detailed and easy-to-understand documentation that guides developers through integration and usage, reducing development time.
  • Scalability
    The service is scalable and can handle a large volume of requests, making it suitable for both small businesses and large enterprises.
  • Free Tier Availability
    Mailboxlayer offers a free tier for developers to test the service, allowing them to evaluate its features before committing to a paid plan.

Possible disadvantages

  • Rate Limiting on Free Tier
    The free tier includes rate limiting, which can be restrictive for businesses needing to process a large number of verifications quickly.
  • Potential Costs
    As usage increases and more features are required, costs can escalate, which might be a concern for businesses with limited budgets.
  • Dependence on Network Connection
    The API requires an active internet connection, which may not be ideal for applications needing offline functionality.
  • Limited Customization
    Some users may find the options for customization limited, restricting the ability to tailor the service to specific business needs.

Analysis

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

IsValid.dev
mailboxlayer API

Overall verdict

  • IsValid.dev appears to be a developer-focused validation/utility tool that can be useful for quick, lightweight validation tasks, though I don't have verified, up-to-date details on its full feature set or reliability track record.

Why this product is good

  • Likely offers a simple, developer-friendly interface for validation tasks
  • Probably free or low-cost, making it accessible for quick checks
  • May support common validation formats (e.g., JSON, schemas, or data formats) useful in development workflows
  • Could save time compared to writing custom validation scripts for simple use cases

Recommended for

  • Developers needing quick, ad-hoc validation checks
  • Small projects or prototypes where a lightweight tool suffices
  • Users looking for a free or low-cost alternative to more complex validation suites
  • Learning or testing purposes rather than mission-critical production validation

No analysis of mailboxlayer API yet.

Category popularity

How often each product is chosen within a category, 0–100% relative to the other.

Score bands 0–20 21–40 41–50 51–60 61–100
IsValid.dev
mailboxlayer API
100% 100%
APIs
0% 0%
0% 0%
Email Verification
100% 100%
100% 100%
API
0% 0%
0% 0%
Email Marketing
100% 100%

Questions & Answers

As answered by people managing IsValid.dev and mailboxlayer API.

What makes your product unique?

IsValid.dev's answer

IsValid offers 70+ validators in a single API — covering financial identifiers (IBAN, BIC, ISIN, LEI), international standards (ISBN, ISSN), technology formats (UUID, JWT, QR codes), tax numbers (VAT, REGON, PESEL), credit cards, phone numbers, and more. No need to integrate multiple services for different data types.

Why should a person choose your product over its competitors?

IsValid.dev's answer

Most validation APIs focus on one category (email or phone). IsValid covers financial, regional, and technical formats all in one place with a consistent REST API. The free tier with 100 calls/day requires no credit card, and integration takes minutes.

How would you describe the primary audience of your product?

IsValid.dev's answer

Developers and software teams building applications that handle user input, financial data, or international identifiers — particularly in fintech, e-commerce, and SaaS products.

What's the story behind your product?

IsValid.dev's answer

IsValid was built out of frustration with piecing together multiple validation libraries and services. The goal was a single, reliable API that handles the full range of data validation needs developers encounter in real-world applications.

Which are the primary technologies used for building your product?

IsValid.dev's answer

Next.js, Fastify, PostgreSQL, Docker

User comments

Share your experience with using IsValid.dev and mailboxlayer API. For example, how are they different and which one is better?

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Social recommendations and mentions

Recommendations tracked on public social media and blogs since March 2021.

IsValid.dev 0 mentions
mailboxlayer API 5 mentions

Tracking IsValid.dev since Apr 2026.

  • What's the easiest way to check if an email exist?
    I've found a few "free" APIs which tell you if the email address exists or not, they have a free tier for certain amount of queries. Try https://mailboxlayer.com and https://www.zerobounce.net. Source: about 4 years ago
  • How to build email validation service with AWS products?
    What I mean by valid is whether it is deliverable or not. Like this https://mailboxlayer.com/. Source: about 4 years ago
  • Laravel validation and custom rules in Inspector
    In Inspector we use the mailboxlayer.com API to validate emails. The service is also able to detect fake email addresses, temporary addresses, and the actual existence of an email address using MX-Records and SMTP. - Source: dev.to / over 4 years ago

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Alternatives to IsValid.dev and mailboxlayer API

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