TL;DR: I built TheTextKit, a free collection of 30 browser-based utilities for text, developers and students. Word counter, JSON formatter, GPA calculator and more. Everything runs locally in your browser, so nothing you type is sent to a server.
Why I built another set of online text tools
Every developer pastes things into random online tools: a JSON payload with API keys, a list of customer emails, an unpublished draft. Most of those tools process your input on a server, and you have no easy way to check.
I wanted the opposite: fast utilities where the text stays on your machine. That became TheTextKit, 30 tools in 7 categories, all client-side.
How TheTextKit keeps your text private
The rule is simple: all processing happens in your browser. Nothing you paste is transmitted to a server.
You can verify it yourself. Open your browser's DevTools, switch to the Network tab, paste some text into the Word Counter, and watch for outgoing requests while it counts.
The Word Counter gives instant word and character counts while the text never leaves your browser.
What's inside: 30 tools in 7 categories
| Category | Tools | Examples |
|---|---|---|
| Analysis & counting | 5 | Word Counter, Reading Time Calculator |
| Case & formatting | 3 | Case Converter, URL Slug Generator |
| Lines & lists | 4 | Remove Duplicate Lines, Sort Lines |
| Developer & web | 9 | JSON Formatter, Regex Tester, Diff Checker |
| Writing & content | 2 | Lorem Ipsum Generator |
| Text extraction | 4 | Extract Emails, Extract URLs |
| Student tools | 3 | GPA Calculator, Grade Calculator |
Every tool follows the same pattern: input → transform → output. That keeps them fast, predictable and easy to maintain.
Developer tools: the JSON Formatter
The JSON Formatter & Validator is probably the tool I use most. Paste raw or minified JSON and it validates and pretty-prints it with 2-space indentation. A toggle switches to minify mode. If the input is invalid, the error points to the exact position of the problem, with no silent failures.
Conceptually, the core is just two built-in calls:
const pretty = JSON.stringify(JSON.parse(input), null, 2); // pretty-print
const mini = JSON.stringify(JSON.parse(input)); // minify
The real work is in the details: clear errors, instant feedback and a one-click copy button.
Pretty-print or minify JSON with clear error reporting, entirely in the browser.
The developer category also includes a Base64 Encoder/Decoder, a URL Encoder/Decoder, a UUID v4 Generator, a Password Generator, and CSV to JSON and JSON to CSV converters.
Student tools: because grades are private too
It might seem odd to put calculators on a text-tools site. But GPAs and grades are personal data, so the same privacy-first approach fits. I added three calculators, each showing its work.
Percentage Calculator
The Percentage Calculator handles three common problems: finding a percentage of a number, finding what percent one number is of another, and calculating percentage increase or decrease. It displays the formula next to each result:
Percentage change = ((new − old) ÷ |old|) × 100
((90 − 75) ÷ 75) × 100 = +20%
Three percentage calculations in one page, each with its formula shown.
GPA Calculator
The GPA Calculator computes semester and cumulative GPA in real time. It supports the unweighted 4.0 scale, weighted Honors and AP/IB courses, plus/minus grading, and prior cumulative credits.
In the example below, four courses totaling 13 credits produce 45.7 quality points, which gives a GPA of 45.7 ÷ 13 ≈ 3.52.
Semester GPA, credits and quality points update as you edit your courses.
Grade Calculator
The Grade Calculator has two modes. The first calculates your weighted course grade across categories like homework, quizzes and exams. The second tells you what score you need on your final exam to hit a target grade.
If your weights don't add up to 100%, it normalizes them automatically. In the example, 75% of the course is graded and the current average is 88.67% (B+).
Weighted categories in, current average and remaining weight out.
Design decisions that paid off
- Show the formula. Users trust a result more when they can see how it was calculated.
- Make errors specific. "Invalid JSON" isn't enough. Pointing to the exact position saves real time.
- Cross-link related tools. Each tool page suggests related utilities, so people who count words also find the reading-time and character counters.
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Keep URLs clean and predictable. Every tool lives at
/tools/<tool-name>, grouped by category. - Update results as you type. Counts, GPA and grades recalculate live, so you see the answer without extra clicks.
FAQ
Does TheTextKit upload my text?
No. All tools run locally in your browser, with zero server transmissions for your input.
Is TheTextKit free?
Yes, all 30 tools are free to use.
How many tools are there?
30, across 7 categories. See the full tools directory.
Can I suggest a new tool?
Yes, use the contact page or leave a comment below.
Try it and tell me what's missing
Browse all 30 tools at thetextkit.com. If there's a text or developer utility you keep wishing existed, tell me in the comments. I'm deciding what to build next.
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