Developer blog posts
Use free online developer tools for JSON formatting, JWT decoding, SQL formatting, HTTP status codes, webhooks, cron expressions, API debugging, and backend workflows.. Browse the posts that support this workflow category across the WebToolsPlanet blog.
Posts in Developer
Published posts in this category.
How to Validate HTML Forms Properly
Validate HTML forms with required, pattern, minlength, and type attributes, plus reportValidity/setCustomValidity — and a hidden-field bug in multi-step forms.
How to Secure a Public Form Endpoint
Secure a public form endpoint — origin/domain checks, rate limiting, request size limits, and data a form should never collect. Free generator included.
Why Form Submissions Are Not Reaching Email
Troubleshoot a contact form that isn't sending email — check name attributes, method, verification, spam, and endpoint config. Free generator included.
How to Handle Form Submissions on a Static Website
Handle form submissions on a static site with no backend — form-endpoint providers, serverless functions, and platform-native handling. Free generator included.
How HTML Form Action and Method Work
How the HTML form action and method attributes work — GET vs POST, when the browser navigates, and submitting without a page reload. Free generator included.
Honeypot vs CAPTCHA for Form Spam
Compare honeypot fields and CAPTCHA for stopping form spam — how each works, what they block, and which to use first. Free generator with honeypot support.
How to Submit a React Form to an API
Submit a React form to an API with fetch — controlled inputs, a submit handler with loading/error states, and honeypot protection. Free generator included.
How to Create an Accessible Contact Form
Build an accessible HTML contact form — linked labels, fieldsets for grouped inputs, aria-describedby help text, and keyboard support. Free generator included.
How to Create a Contact Form in Next.js
Build a Next.js App Router contact form — controlled inputs, validation, honeypot protection, and a Route Handler backend. Free generator included.
How to Send an HTML Form to Email Without PHP
Send HTML form submissions to your email without PHP or a backend server — required markup, endpoint setup, spam protection, and a free form generator.
How to Fix Invalid JSON: Common Errors and Examples
Fix invalid JSON fast. Learn the most common JSON syntax errors — trailing commas, missing quotes, bad nesting — with real examples and a free online validator.
How IBAN Checksum Validation Works (mod-97 Explained)
A step-by-step walkthrough of the ISO 13616 mod-97 algorithm used to validate IBAN check digits, with a worked example.
IBAN vs SWIFT/BIC: What Is the Difference?
IBAN and SWIFT/BIC are both used in international transfers but identify different things. Learn the difference and when international payments need both.
What Is an IBAN? A Practical Guide for Developers
Understand what an IBAN is, how it is structured, why the check digits exist, and how to generate safe fake IBANs for development and QA testing.
How to Decode JWT Tokens Safely
Decode a safe demo JWT token, inspect common claims, and learn what not to paste into an online JWT decoder.
What Is SQL Formatting and Why It Matters
Understand what SQL formatting actually changes, when it helps most, and why clean query layout matters for debugging, reviews, and team workflows.