
JSONFormatter.org
JSONLint
JSON Editor Online
JSON Formatter & Validator
betterjson.com
MockRest
SafeJSON.dev
Easily format, validate, and beautify JSON data with our free online tool. Includes powerful JSON conversion features for seamless data management

Decode and verify SSL/TLS certificates online. Extract X.509 details including issuer, validity, SAN, and fingerprint. Fast, secure, and browser-based.
Which is more popular?
Based on our record, Format JSON Online should be more popular than Cert Decoder. It has been mentioned 2 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | formatjsononline.com | certdecoder.com |
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| Platforms | — | |
| Company | 2025 | — |
| Listed in |
In their own words, as submitted to SaaSHub.


Format JSON Online is a fast, free, and privacy-focused tool to format, validate, minify, and beautify JSON data directly in your browser. Built for developers and API testers, it offers support for large JSON files without requiring login or sending data to a server. Additional features like...
Cert Decoder is a free online tool that helps you decode X.509 SSL/TLS certificates in PEM format. It instantly shows important information like the issuer, expiry date, SAN entries, and fingerprint. All data is processed locally in your browser, so nothing is ever sent or stored elsewhere.
What each product offers, as listed by its team.


No features have been listed yet.
Possible disadvantages
An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
Overall verdict
Why this product is good
Recommended for
Walkthroughs and reviews on video.
Best Free JSON Formatter Online | Format, Validate & Minify JSON Instantly
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How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing Format JSON Online and Cert Decoder.
Format JSON Online's answer
The idea came while working on multiple API integrations where formatting large JSON responses quickly became frustrating. Most existing tools either lagged, required uploading sensitive data, or were filled with ads. FormatJSONOnline was built as a clean, fast, and secure alternative that works instantly, with no signup, no tracking, and no BS.
Cert Decoder's answer:
I built certdecoder.com over the weekend for my own needs. Sometimes in my work, I need to verify and check certificate details.
Format JSON Online's answer
React.js (for UI and client-side rendering)
Tailwind CSS (for fast and clean styling)
Next.js (for performance and SEO)
Vercel (for deployment and CDN optimization)
Cert Decoder's answer:
certdecoder.com was built using just JavaScript and HTML—simple, fast, and with all processing happening locally in your browser, so no certificate data is sent to any server
Format JSON Online's answer
The primary audience includes:
Front-end and back-end developers
API testers and engineers
Data analysts and tech leads
Students and hobby coders working with JSON
Cert Decoder's answer:
certdecoder.com is primarily built for developers, sysadmins, cybersecurity enthusiasts, and DevOps engineers.
Format JSON Online's answer
Unlike many JSON tools that are bloated, ad-heavy, or slow, FormatJSONOnline is:
Blazing fast, even for large (20MB+) files
Privacy-focused, with zero data sent to any server
Minimalist and distraction-free
Mobile and tablet responsive It’s designed specifically for developers who value performance and simplicity.
Cert Decoder's answer:
Simple, fast, and reliable. Some similar tools can’t even decode basic certificates. I rigorously tested my tool with many real-world certificates and covered several edge cases where competitors fall short.
Format JSON Online's answer
FormatJSONOnline is used by developers and teams across companies and institutions, though exact names aren’t tracked due to privacy-first architecture. However, notable daily users include:
Developers from GitHub
Engineers at Microsoft (based on public traffic data)
API testers from Postman community
Students from Indian Institutes of Technology (IITs)
Indie hackers and open-source contributors
Cert Decoder's answer:
certdecoder.com is primarily built for developers, sysadmins, cybersecurity enthusiasts, and DevOps engineers.
Format JSON Online's answer
FormatJSONOnline is uniquely optimized for speed, privacy, and simplicity. It processes even large JSON files with minimal delay, works entirely on the client-side (nothing is sent to a server), and offers formatting, validation, minification, and copy-to-clipboard — all in one place with zero tracking or ads.
Share your experience with using Format JSON Online and Cert Decoder. For example, how are they different and which one is better?
Recommendations tracked on public social media and blogs since March 2021.


In this guide, you'll learn how to format, validate, and manipulate JSON data in your browser using Format JSON Online, a fast, privacy-first tool for developers. - Source: dev.to / about 1 year ago
This list spans the entire frontend dev lifecycle—learning, coding, designing, testing, and deploying. Tools like Format JSON Online are clutch for handling JSON data, a common task when building API-driven apps. Save these links, and... - Source: dev.to / about 1 year ago
Why? Because I built certdecoder.com and couldn’t find a decent place to submit it. So I said screw it — I’ll build my own. With blackjack and hookers. - Source: dev.to / over 1 year ago
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