My Daily Developer Tool Belt (And Why Browser-Based Wins)

I have been writing software for years, and over time my "tool belt" - the small utilities I reach for several times a day - has narrowed to maybe ten tools. They are not glamorous. None of them would make it onto a "must-have AI tools for developers in 2026" listicle. They are the boring, reliable utilities that turn a 20-minute task into a 30-second task, every day.

Almost every one of them is now available as a browser-based tool that does not require an install or an account. That trend is the actual story of developer tooling in 2026: the things that used to require a desktop install can now run as fast or faster as a web page. Here is the list, with notes on which ones I use, why, and where the Toolium versions came from for the ones that did.

JSON formatter and validator

The single tool I open most often. Paste a JSON blob from a server response, see it pretty-printed with syntax highlighting, find the syntax error if any. The Toolium JSON Formatter handles inputs up to a few megabytes comfortably; for larger inputs jq on the command line is faster.

What makes a JSON formatter good versus mediocre: error messages that point at the line and column of the syntax error rather than just "JSON parse failed"; preservation of key order rather than alphabetical reordering; and the ability to copy the formatted output in one click.

JSON visualizer (the diagram one)

For deeply nested API responses, reading raw JSON is exhausting. The JSON Visualizer renders the structure as a node-link diagram laid out with Dagre. Each object is a box; each key is an edge to the nested value. It lets you see the shape of a complex response at a glance and zoom into the bits that matter.

I use this when I am trying to understand an unfamiliar API's response structure or when I need to communicate the shape of a payload to a teammate without sending the whole blob.

Regex tester

Regex is the kind of thing where five minutes of tinkering replaces an hour of writing a parser. The Regex Tester runs your regex against your test input in real time, highlighting matches and capture groups as you type. The killer feature is the Web Worker timeout that prevents catastrophic-backtracking patterns from freezing your tab - the long version of why this matters is in my post on regex.

Base64 encoder/decoder

For inspecting JWT tokens, debugging data URIs, decoding email headers, or just converting binary blobs to text for testing. The Toolium Base64 tool handles UTF-8 correctly (most browser-based base64 tools mishandle non-ASCII characters because they use btoa naively; the right approach is to UTF-8 encode first, then base64).

JWT decoder

For auth debugging. The JWT Decoder splits a token into its three sections, decodes each, and shows the header and payload as formatted JSON. Critically, it does NOT try to verify the signature - that would require a secret key the user shouldn't paste into a web tool. For verification, command-line jwt-cli is the right tool.

URL encoder/decoder

Less commonly needed than JSON or base64, but when you need it, you really need it. The URL Encoder handles the encodeURI vs encodeURIComponent distinction, which is the part most people get confused about. For 95% of uses, you want encodeURIComponent.

Diff checker

For comparing two versions of a config file, two API responses to see what changed, two paragraphs of text to spot a single-character difference. The Toolium Diff Checker does line-level diffing with word-level highlighting on near-matches. The comparison is bounded: past about four million LCS cells, roughly a 2,000-by-2,000-line changed region once identical prefixes and suffixes are trimmed, the tool refuses rather than freezing the tab.

Color picker

Picking colors and converting between HEX, RGB, and HSL representations. The Toolium Color Picker handles the three-digit hex format (#F63) that surprisingly many tools fail to parse. The HSL representation is the most useful for design work because you can adjust saturation or lightness without changing the hue.

Password generator

For generating new account passwords. I use my password manager's built-in generator most of the time, but the standalone tool is useful when I need a password but the manager is not open, or when I am generating a password I want to share with someone via a side channel.

Hash generator

For computing SHA-256 of a string (verifying a file matches a published hash, generating a deterministic identifier from a known input). The Toolium Hash Generator does SHA-256, SHA-512, SHA-1, and MD5 in the browser using the SubtleCrypto API.

UUID generator

For generating identifiers when seeding test data or writing example documents. The UUID Generator produces v4 (random) or v7 (time-ordered) UUIDs using the browser's secure random source.

Timestamp converter

For converting between Unix timestamps and human-readable dates. Critical when debugging log entries or examining JWT exp claims. The Timestamp Converter auto-detects seconds vs milliseconds vs microseconds.

Why I prefer browser-based versions

The desktop versions of all these tools exist - jq, Python with various libraries, the regex tester built into VS Code, etc. - and for some tasks the desktop tools are faster. But for the kind of one-off, debugging-oriented use that takes up most of my "tool reaches" during a workday, the browser-based version wins on:

• No install. I can use Toolium from any machine I sit down at, including a friend's laptop or a public computer.
• No privacy compromise. Browser-based tools that run client-side (like Toolium) keep my pasted data on my machine. The desktop tools do too, of course; the difference is that I can verify the network behavior of the browser tool by opening the network tab.
• Up-to-date. Browser versions get updated automatically. No version pinning, no homebrew updates, no "I should really update this tool I haven't used in six months."
• Linkable. When explaining something to a teammate, I can paste a Toolium URL and they have the same tool with one click.

The full list of Toolium tools is on the tools page. The methodology behind how I built them is on the methodology page.