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136 free online tools for developers and QA engineers.
JSON formatter, regex tester, UUID generator, and more.
{
"status": "healthy",
"version": "1.0.0",
"service": "softwaretesttips-web"
} > 136 tools · 17 categories · 100% client-side
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JSON Formatter
Format, validate, and beautify JSON with syntax highlighting
Regex Tester
Test regular expressions with real-time matching and explanations
UUID Generator
Generate UUID v1, v4, v5 with bulk export options
Base64 Encoder
Encode and decode Base64 strings instantly
Timestamp Converter
Convert between Unix timestamps and human-readable dates
Hash Generator
Generate MD5, SHA-1, SHA-256, SHA-512 hashes
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Accessibility
A11y testing tools
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Analyze and inspect code and data
Diff & Compare
Compare text and data
Converters
Transform data formats
Encoders
Encode and decode data
File Tools
Convert, process, and transform files client-side
Formatters
Beautify and format code
Generators
Create test data and IDs
Image Tools
Image processing tools
Legal
Legal document generators
Minifiers
Compress and optimize code
Network
Test APIs and endpoints
Reference
Developer references
SEO Tools
Search engine optimization
Testing
Testing and QA helpers
Utilities
Developer utilities
Validators
Test and validate patterns
Start with the job, not the tool
Most tool directories ask you to browse. This one works the other way round: name the job in front of you, then open the category that does it. Every tool runs in the tab you already have open, so nothing you paste into a formatter, a validator or a hash generator is uploaded anywhere.
Inspect data you already have
When something breaks, the evidence usually arrives already written: a minified payload, a malformed CSV, a token you did not mint. The formatters rebuild that text into a shape you can read, the validators say what is wrong and where instead of only that it is wrong, and the converters move the same payload between JSON, CSV, XML, YAML, Base64 and Unix timestamps.
Produce data that looks like production
Fixtures built from three hard-coded values hide the bugs you are hunting. The generators produce the awkward inputs instead: UUIDs in the current RFC 9562 form, passwords at the length NIST allows, SHA-2 and HMAC output, QR codes, gradients and placeholder personas, ready to paste into a seed script.
Check how a running system replies
A network tool does not measure the internet. It sends one query to one authority and prints the answer, which is why knowing the authority matters. The network tools do live lookups - DNS records, RDAP registration data, certificate transparency logs, response headers, CORS behaviour - while the SEO tools generate and check robots.txt, XML sitemaps and structured data, and the accessibility tools test contrast and colour-vision behaviour against WCAG.
The published rule behind each check
A tool that only says "invalid" is offering an opinion. Where a standard exists, these tools apply the published number rather than a house rule, and the table below names that rule and the sentence it comes from.
| Check | What the published rule says | Source |
|---|---|---|
| HTTP header and status inspector | "Field names are case-insensitive" - a checker that compares header names by exact case reports a present header as missing. | RFC 9110 section 5.1 |
| Email address validator | "The maximum total length of a user name or other local-part is 64 octets", and the whole forward-path is capped at 256 octets - not the 320 characters most forms enforce. | RFC 5321 section 4.5.3.1 |
| Colour contrast checker | Normal text needs a contrast ratio "of at least 4.5:1"; large-scale text needs 3:1, which is why the same pair of colours can pass one size and fail another. | WCAG 2.2 SC 1.4.3 |
| XML sitemap generator | Each sitemap file "must have no more than 50,000 URLs and must be no larger than 50MB (52,428,800 bytes)" - the bytes are the harder limit once URLs carry long query strings. | sitemaps.org protocol |
| robots.txt tester | A crawler's parsing limit "MUST be at least 500 kibibytes", and "The last group may have no rules, which means it implicitly allows everything" - a trailing empty group overrides the block you wrote above it. | RFC 9309 section 2.2.1 |
The longer versions of that argument live in the guides: what makes a test case fail for the right reason, where regression testing ends and smoke testing begins, and how to test a JSON API without writing code.
Sources: RFC 9110 section 5.1, RFC 5321 section 4.5.3.1, WCAG 2.2 success criterion 1.4.3, the sitemaps.org protocol page, RFC 9309 section 2.2.1. Every page was read in full before the sentence above was quoted.
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