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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.

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Edge computing is the new frontier.

Which is more popular?
Based on our record, Fly.io seems to be more popular. It has been mentioned 483 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | isvalid.dev | fly.io |
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| Platforms | — | |
| Company | — | Startup from the United States |
| Listed in |
In their own words, as submitted to SaaSHub.


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),...
No description of Fly.io yet.
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Recommended for
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We FLY a SPACESHIP! Video Game FLY.io Computer App with HobbyKidsTV
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing IsValid.dev and Fly.io.
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.
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.
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.
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.
IsValid.dev's answer
Next.js, Fastify, PostgreSQL, Docker
Share your experience with using IsValid.dev and Fly.io. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


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Yes! Several platforms offer real free tiers in 2026. SnapDeploy gives you free containers (no time limits) with no credit card required — and your hours only count when your app is running. Render offers free web...
Fly.io is one the best free alternatives to Heroku that you can use. It’s designed for developers and students to run small applications for free and scale costs affordably as you grow. Just like Heroku it comes with...
Recommendations tracked on public social media and blogs since March 2021.


Tracking IsValid.dev since Apr 2026.
Go 1.26 standard library, modernc.org/sqlite for a pure Go SQLite, and solana-go for the RPC client, transaction building and the SPL Memo instruction. React 19, Vite 8, TypeScript 7 and Tailwind CSS 4 on the page. Alegreya and IBM Plex,... - Source: dev.to / about 1 month ago
Fly.io opens up two things Heroku keeps at arm's length: real multi-region deployment and full control over the runtime. Heroku's Common Runtime offers two regions (US and EU), and Private Spaces gets you one region at a time from a... - Source: dev.to / 3 months ago
The gateway is the web service that receives requests. I host it on Fly. It accepts Slack events, automation API calls, trigger requests, Composio webhooks, Inngest calls, and runtime calls. - Source: dev.to / 4 months ago
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Vercel is the platform for frontend developers, providing the speed and reliability innovators need to create at the moment of inspiration.
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