JSON Studio
Format, validate, minify, query and compare JSON in your browser, with precise line-and-column errors.
Developer ToolsDeveloper Tools
Developer Tools are the utilities you reach for mid-debugging: when an API returns malformed JSON at midnight, when a regex matches too much, or when an email lands in spam and the trail leads to DNS records. JSON Studio handles the full JSON workflow — formatting with your choice of indentation, validation that names the line and column of the first error, a collapsible tree, JSONPath queries and a structural compare that reports added, removed and changed paths instead of an unreadable text diff. The Regex Tester guards against the classic accident, catastrophic backtracking, by running patterns in a Web Worker with a one-second timeout. The Security Header and DNS Checker is the one server-side tool here: it fetches a URL's response headers and a domain's public DNS records — SPF, DKIM and DMARC included — and explains each finding in plain language. Two of the three tools never see your data at all; the third fetches only public information and says exactly what it does.
Tools in this category
Regex Tester
Test patterns against sample text with match highlighting, capture groups and a safe one-second timeout.
Developer ToolsSecurity Header and DNS Checker
Check HSTS, CSP and other security headers, TLS details, and DNS/email authentication records (SPF, DKIM, DMARC).
Developer ToolsPassword Generator
Generate strong passwords with length and character-set controls, an honest entropy estimate and a session-only history.
Developer ToolsBase64 Studio
Encode or decode Base64 text and files with URL-safe alphabet support and precise, positioned error messages.
Developer ToolsWhich tool should I use?
| Tool | Use it when you need to… |
|---|---|
| JSON Studio | Format, validate, explore, query and compare JSON, with exact line-and-column error locations. |
| Regex Tester | Test JavaScript regular expressions with highlighted matches, group tables and a backtracking timeout. |
| Security Header and DNS Checker | Inspect a URL's security headers and TLS setup, and check a domain's SPF, DKIM and DMARC records. |
Working notes
Keep these three open in the tabs where you already work. JSON Studio replaces the paste-into-a-random-website habit with something safer: your payloads never leave the machine, which matters the first time a response body contains a customer's email address. The regex tester's timeout exists because a pattern that hangs for thirty seconds in a browser tab will hang the same way in production code. And when an email-authentication check is part of an incident, the DNS checker's plain-language output is written so you can paste it straight into the ticket.
Related articles
How to Format and Validate JSON
JSON syntax rules in plain language, a formatting workflow, and a gallery of 10 common errors — each one executed in Node against the JSON Studio validator code, with the line, column and hint it returned, and the fix that makes it parse.
How to Use Regular Expressions Safely
Regex tokens, groups and flags explained with tested matches — then the safety part most guides skip: catastrophic backtracking measured on a real pattern (0.11 ms at 10 characters, 2,115 ms at 28), why a one-second timeout matters, and the rewrite that makes the same check instant.
How to Configure HTTP Security Headers
Six response headers do most of the browser-enforced hardening for a website. What each one stops, the values real sites send — captured live — and copy-ready Apache and Nginx configuration.
Frequently asked questions
Where does my JSON get processed?
Your own machine. JSON Studio and the Regex Tester run entirely in the browser, and large JSON is processed in a Web Worker so the page stays responsive. Nothing is uploaded.
The JSON validator says my file is invalid. How do I find the problem?
The note under the result shows the exact line and column, plus a plain-language hint about the likely cause — a trailing comma, single quotes, or an unclosed bracket are the usual suspects.
Is the Security and DNS Checker a penetration test?
No. It checks configuration — headers, TLS validity dates and published DNS records — and explains what each one means. It does not probe for vulnerabilities, and the tool page says so explicitly.