VS Code
CodePen
GitHub
Node.js
RegExr
JSFiddle
CodeSandbox
Free ebook for the JS Beginners

VatStack
VATnode.dev
vatlayer API
EuroCompta.eu
Justaxit
Validate Vat
The VAT API
EU VAT validation with audit-proof VIES certificates

Which is more popular?
Based on our record, Eloquent JavaScript seems to be more popular. It has been mentioned 218 times since March 2021.
Website, pricing, platforms and company facts side by side.
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Eloquent JavaScript
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| Website | eloquentjavascript.net | viesac.eu |
| Pricing | ||
| Company | — | Startup from Estonia · 2026 |
| Listed in |
In their own words, as submitted to SaaSHub.

No description of Eloquent JavaScript yet.
VIESAC helps EU B2B businesses validate VAT numbers, generate VIES audit certificates, and store compliance proof for cross-border 0% VAT invoices. VIESAC is a cloud service for EU VAT number validation, VIES audit proof, and compliance storage. It helps B2B sellers, accountants, SaaS platforms,...
What each product offers, as listed by its team.

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Walkthroughs and reviews on video.
Eloquent JavaScript A Modern Introduction to Programming 3rd Edition by Marijn Haverbeke review
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As answered by people managing Eloquent JavaScript and VIESAC.
VIESAC's answer:
VIESAC goes beyond basic VAT number validation by combining real-time checks, resilient fallback routing, and audit-ready evidence in one platform.
Unlike standard VAT lookup tools, VIESAC can automatically use alternative official registries when VIES is unavailable, helping businesses keep validation workflows running without interruption.
Each verification can be stored with timestamped evidence and generated as a professional PDF or XML certificate for audits, tax reviews, and internal compliance.
VIESAC also supports API integrations, WooCommerce, Google Sheets, EORI validation, monitoring, and country-specific business registries — making it suitable for both occasional checks and automated high-volume compliance workflows.
The focus is not only on answering “Is this VAT number valid?” but on providing reliable, reusable proof of the verification.
VIESAC's answer:
VIESAC is built for businesses that need more than a simple VAT lookup.
It combines VAT and EORI validation, SmartRouter™ fallback checks, audit-ready PDF/XML certificates, monitoring, API access, and integrations in one platform.
A key advantage is reliability: when VIES is unavailable, VIESAC can use alternative official sources where supported, reducing failed checks and interruptions.
It also keeps structured evidence of each verification, so businesses can demonstrate when and how a VAT number was checked during audits, tax reviews, or internal compliance processes.
Compared with basic validation services, VIESAC focuses on the complete compliance workflow — from verification to evidence, monitoring, and automation — while remaining simple enough for occasional manual use.
VIESAC's answer:
VIESAC is primarily designed for businesses that regularly sell to, buy from, or verify companies across borders and need reliable VAT compliance evidence.
Typical users include e-commerce businesses, wholesalers, logistics companies, automotive traders, accounting and tax teams, procurement departments, universities, public-sector organizations, and software platforms that need automated VAT or EORI validation.
It is especially useful for companies handling EU B2B transactions, reverse-charge sales, supplier onboarding, customer verification, or recurring compliance checks.
VIESAC serves both small businesses that need occasional verified checks and larger organizations that require API integrations, monitoring, audit trails, and higher-volume automated workflows.
VIESAC's answer:
VIESAC started from a simple problem: VAT validation is easy when everything works, but real-world compliance is much more complicated.
Businesses need to know not only whether a VAT number is valid, but also when it was checked, which source confirmed it, what happened if VIES was unavailable, and whether they can prove the verification later during an audit.
VIESAC was built to solve that gap.
What began as a reliable VAT validation service gradually evolved into a broader compliance platform with audit-ready evidence, PDF and XML certificates, monitoring, API access, EORI validation, country-specific registries, and integrations for business workflows.
The goal has remained the same from the beginning: make cross-border VAT verification more reliable, easier to automate, and easier to prove.
VIESAC's answer:
VIESAC is built around modern web and integration technologies, including REST APIs, webhooks, OAuth-based integrations, structured JSON/XML data exchange, and cloud-based automation.
The platform connects with official VAT, EORI, tax, and business registries and supports integrations with e-commerce, spreadsheets, automation platforms, and other business systems.
VIESAC is designed to work both as a standalone web application and as an API-first compliance service that can be embedded into existing business workflows.
VIESAC's answer:
VIESAC is used by businesses and organizations across several sectors, including automotive and vehicle trading, logistics and freight, wholesale and distribution, e-commerce, accounting and tax advisory, legal services, universities, and public-sector organizations.
The platform is particularly relevant for companies that handle frequent cross-border B2B transactions and need reliable VAT or EORI validation together with audit-ready evidence.
VIESAC is also used by larger organizations evaluating API-based or automated compliance workflows for higher-volume verification.
Share your experience with using Eloquent JavaScript and VIESAC. For example, how are they different and which one is better?
Recommendations tracked on public social media and blogs since March 2021.

If you haven’t read Eloquent JavaScript , go check it out. It’s one of my all-time favourite programming books — hands down. - Source: dev.to / about 1 year ago
Videos, blogs, text-based teachings, YouTube project-based learning, books, and the like are all examples of various methods and mediums of acquiring skills, especially in the software engineering industry. As I continue to navigate... - Source: dev.to / almost 2 years ago
Seconded. I won't recommend it and no one I know has recommended it for a decade. It's hard for someone who doesn't know JS to know which parts has changed and is no longer the way to do things. https://github.com/getify/You-Dont-Know-JS... - Source: Hacker News / about 2 years ago
Tracking VIESAC since Mar 2026.
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