# Developer Tools — CapyToolkit Blog

For the full blog, see: [Blog](https://capytoolkit.com/blog/)

[Debugging API Responses Locally in the Browser: A JSON Formatter Workflow That Never Sends Your Payload](https://capytoolkit.com/blog/developer-tools/debugging-api-responses-locally-browser-json-formatter-workflow/): A three-minute local debugging routine for API responses: format, validate, locate the broken line, browse large payloads as a tree, and minify.
[Running an LLM in Your Browser: Verifying WebGPU, Model Hashes, and Local Inference Without a Server](https://capytoolkit.com/blog/developer-tools/running-llm-browser-verifying-webgpu-model-hashes-local-inference/): Verify a local browser LLM before you trust it: check WebGPU support, hash the model file, and audit what your browser leaks while it runs.
[UUID v4 or v7 as a Primary Key: What Changes in Your Index, Your Logs, and Your URLs](https://capytoolkit.com/blog/developer-tools/uuid-v4-v7-as-primary-key-what-changes-your-index-your-logs-your-urls/): The UUID version digit decides how your index absorbs writes, what a public identifier reveals, and how keys behave in logs and exports.
[Local-First Data Analysis in the Browser: SQL Workbench and Big Log Explorer for Zero-Upload Analytics](https://capytoolkit.com/blog/developer-tools/local-first-data-analysis-browser-sql-workbench-log-explorer/): Run SQL on Parquet, CSV, and JSON in your browser. Combine with Big Log Explorer for a zero-upload analytics stack that keeps your data local.
[Finding the Correct MIME Type for Any File Before You Serve or Upload It](https://capytoolkit.com/blog/developer-tools/finding-the-correct-mime-type-file-before-you-serve-upload-it/): Look up the exact MIME type for any file, extension, or keyword, then copy a correct server directive. No upload, no server round-trip.
[Reading HTTP Status Codes Like a Backend Engineer: A Local Reference Guide You Can Use Without a Network](https://capytoolkit.com/blog/developer-tools/reading-http-status-codes-backend-engineer-reference-guide-network/): Learn to read HTTP status codes by class, distinguish confusing code pairs, and apply the right codes in API design and six popular frameworks.
[What Happens to Your Prompt When You Use an Online Token Counter](https://capytoolkit.com/blog/developer-tools/what-happens-to-your-prompt-online-token-counter/): Your prompt travels to a server you don't control before you get a token count. Here's what that means and how to count tokens locally across 37 AI models.
[How Java Developers Use Client-Side Case Conversion for Clean Code and Configuration Files](https://capytoolkit.com/blog/developer-tools/java-developers-use-client-side-case-conversion-clean-code-configuration-files/): Java naming conventions demand camelCase, PascalCase, and SCREAMING_SNAKE. Here is how to convert between them locally without sending code to a server.
[Query Local Files with SQL in the Browser Using CapyToolkit's SQL Workbench](https://capytoolkit.com/blog/developer-tools/query-local-files-sql-browser-capytoolkit-workbench/): Run DuckDB SQL on Parquet, CSV, Excel, JSON, and eight more file formats in your browser. No install, no upload, no server. Just open a tab and query.
[Hash Functions in the Browser: How to Use CapyToolkit's Client-Side Hash Generator for Integrity Checks and HMAC Signatures](https://capytoolkit.com/blog/developer-tools/hash-functions-browser-capytoolkit-hash-generator-integrity-hmac/): How hash functions work, which algorithms are safe in 2026, how HMAC protects webhooks and APIs, and how to run it all locally with CapyToolkit.
[Base64 Encoding Without the Cloud: What Your Browser Handles Locally](https://capytoolkit.com/blog/developer-tools/base64-encoding-without-the-cloud-what-your-browser-handles-locally/): How Base64 encoding works at the byte level, why client-side browser encoding eliminates data exposure, and practical workflows for sensitive data.
[Debugging 500 MB+ Application Logs in the Browser Without Uploading](https://capytoolkit.com/blog/developer-tools/debugging-500-mb-application-logs-in-the-browser-without-uploading/): Filter and search gigabyte-scale log files locally in your browser with Web Workers and IndexedDB, zero uploads, no server, no PII exposure on the wire.
[Counting Prompt Tokens Locally Before Sending to GPT, Claude, and Gemini](https://capytoolkit.com/blog/developer-tools/counting-prompt-tokens-locally-gpt-claude-gemini/): Count tokens, context usage, and input costs for 35+ AI models entirely in your browser before any prompt reaches an API. Prices updated daily, works offline.
[Testing WebRTC Peer-to-Peer Connection Quality Without Cloud Relay Servers](https://capytoolkit.com/blog/developer-tools/testing-webrtc-peer-peer-connection-quality-cloud-relay-servers/): Measure direct browser latency, jitter, and packet loss with zero-cloud WebRTC tools. No servers, no uploads, no TURN relay.
[Debugging and Exploring Parquet Files with Local SQL Queries](https://capytoolkit.com/blog/developer-tools/debugging-and-exploring-parquet-files-with-local-sql-queries/): Query and debug Parquet files locally with SQL, inspect schemas, validate data, catch errors before they reach production.
[Client-Side Cron Expression Parsing for Developer Workflow Automation](https://capytoolkit.com/blog/developer-tools/client-side-cron-expression-parsing-for-developer-workflow-automation/): Learn to validate cron expressions locally with CapyToolkit's parser, avoiding sensitive schedule exposure and catching errors before deployment.
[Converting Color Spaces for CSS and Design Workflows](https://capytoolkit.com/blog/developer-tools/converting-color-spaces-for-css-and-design-workflows/): Understand HEX, RGB, HSL, HSV, OKLCH and when to use each format in production CSS. Includes client-side workflow tips using CapyToolkit's converter.
[Deep JWT Inspection Without Transmission: Client-Side Token Analysis with CapyToolkit](https://capytoolkit.com/blog/developer-tools/deep-jwt-inspection-without-transmission-jwt-decoder-capytoolkit/): Inspect JWT tokens locally: no upload, no network, full privacy. Decode headers, claims, and expiry in-browser for debugging, development, and documentation.