Built by a developer, for developers

The developer behind this site

My name is Pankaj Kumar. I'm a Senior Software Engineer based in Bangalore, India. I have been writing production C# professionally since 2022, working across ASP.NET Core, Blazor (Server and WebAssembly), Entity Framework Core, and Azure-hosted services. My day job involves building and maintaining web APIs, Blazor applications, and Azure-hosted services for enterprise clients.

Most of my actual work hours involve the small but time-consuming tasks that every .NET developer faces: formatting a minified JSON response from a third-party API, decoding a JWT to check why validation is failing, converting a Unix timestamp to a human-readable date, or testing a regex before it goes into production. These tasks take 30 seconds each with the right tool and 10 minutes each without one.

I built DevToolsHub because the tools I was using were consistently slow, covered in ads, or required me to paste sensitive data — JWT tokens, API keys embedded in JSON payloads, private key hashes — into sites I had no visibility into. I wanted tools I could use at work without second-guessing where my data was going. That's the site you're using now.

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Tools I use daily

Here's what's actually running on my machine during a typical working day:

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What DevToolsHub is

DevToolsHub is a free collection of browser-based developer utilities at www.devtoolshub.info. Every tool does one thing well: accept developer input, process it correctly, and return the result immediately.

• Formatting — JSON, YAML, HTML, CSS, SQL, and XML formatters that handle real-world messy input
• Security & Auth — JWT decoder, JWT generator, JWT secret generator, HMAC hash tools
• Encoding & Hashing — Base64, URL encoder, HTML entity encoder, SHA-256/SHA-512/MD5 generator
• Conversion — Unix timestamp converter, CSV to JSON, number base converter, colour space converters
• Generation — UUID/GUID (v1, v4, v5), password generator, QR code generator, cron expression builder
• Text & Code — Regex tester with match highlighting, string escape/unescape, text case converter, text diff
• Web utilities — URL parser, Unix file permissions calculator, Markdown previewer, IP subnet calculator
• Image utilities — colour picker from image, image to Base64, PNG to SVG, SVG to PNG

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How tools are built and verified

1. Requirement definition — I document what the tool should accept, what it should produce, and what edge cases it must handle (malformed input, empty input, large input, non-ASCII characters)
2. Implementation — Tools use established .NET libraries or browser-native APIs. JSON processing uses System.Text.Json. Hashing uses System.Security.Cryptography. Image processing uses the Canvas API. No crypto primitives written from scratch.
3. Manual testing against real-world input — Each tool is tested with actual data I've collected from production work: minified API responses, real JWTs from production systems, actual regex patterns, genuine timestamps from various systems
4. Content review — Educational content is written from personal experience and verified against the relevant RFC or technical standard
5. Security review — Tools handling security-sensitive input (JWTs, passwords, hashes) include explicit usage warnings and known misuse patterns

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The technical architecture

DevToolsHub is built on ASP.NET Core 8 with Blazor Interactive Server and MudBlazor for components. The choice of Blazor Server was deliberate: it enables a reactive UI without shipping a WebAssembly payload, and keeps all tool logic on the server side of the circuit in a single C# codebase — the same language I work in all day.

Code editor panels — used in JSON Formatter, YAML Formatter, HTML Formatter, SQL Formatter, Regex Tester, and several other tools — are powered by Monaco Editor, the same editor that runs inside Visual Studio Code.

There is no database. Tool processing happens entirely in-session, in-memory, and is discarded when the Blazor circuit closes. The only persistent storage is localStorage for theme preferences and recently-used tools, which never leaves the browser.

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Privacy by design

The privacy model is an engineering constraint, not a legal afterthought. Every tool was designed under the assumption that the user might be pasting sensitive data: a JWT from a production system, a JSON response containing API keys, a password being evaluated for strength.

This means: no server-side logging of tool inputs, no database writes of user data, no analytics events that capture input content, and no third-party SDKs with DOM access where inputs are rendered. Analytics tools in use (Google Analytics 4 and Microsoft Clarity) are configured to exclude input field content and are fully disclosed in the Privacy Policy.

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The developer blog

The DevToolsHub developer blog publishes practical technical articles written from hands-on .NET production experience. The "war story" series covers real bugs I've debugged in production: a JWT clock-skew failure that caused intermittent 401 errors across services, a Base64 encoding bug that silently corrupted Azure Blob Storage filenames, an EF Core query that would have updated 2.7 million rows without a WHERE clause.

Articles are published when there's something genuinely worth explaining — a topic that's consistently misunderstood, a common mistake that causes real bugs, or a concept that's poorly documented elsewhere. The goal is evergreen content that remains accurate and useful two years after it's published.

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Monetisation and sustainability

DevToolsHub is free to use and all tools will remain free. The site uses Google AdSense to display non-intrusive advertisements that cover hosting, infrastructure, and domain costs.

There are no paywalled tools, no premium tier, no email capture, and no dark patterns. If you find a tool useful, sharing it with a colleague is the best way to support the site.

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Get in touch

Found a bug? Have a tool request? Want to contribute an article? Use the contact form or email [email protected] directly. I read every message and respond to bug reports within 48 hours.

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