OwlTheEngineer

Free Tools

Developer utilities, built for the real stack.

Fast, zero-tracking, client-side developer utilities designed for backend engineers, DevOps specialists, and AI builders. No popups, no signups required.

Client-side →

JWT Decoder

Decode and inspect JSON Web Tokens instantly in your browser. Pure client-side parsing with expiration countdown, header/payload breakdown, and claim formatting. Zero network requests.

JWTAuthSecurityBase64
Generator →

JSON to TypeScript

Convert JSON objects into clean, strongly typed TypeScript interfaces or type aliases. Handles deep nesting, union types, optional fields detection, and array type inference.

TypeScriptJSONTypesFrontend
Schedule →

Cron Expression Generator

Interactive visual cron schedule builder and human-readable cron expression translator. Preview the next 5 execution timestamps and pick from standard production presets.

CronDevOpsBackendAutomation
Tester & Code →

Regex Generator & Tester

Interactive regular expression builder, tester, explainer, and multi-language code generator. Real-time match highlighting, capture group extraction, and preset library.

RegexDeveloperValidationBackend
UUIDv7 & Inspector →

UUID & ULID Generator

Generate and decode RFC 9562 UUIDv7 (timestamp-ordered), RFC 4122 UUIDv4, ULID, and NanoID. Zero B-Tree index fragmentation for modern database primary keys.

UUIDv7DatabaseULIDBackend
System Sizing →

System Design Capacity Calculator

Calculate throughput (QPS), Peak multipliers, ingress/egress network bandwidth, 5-year storage growth with replication, and 80/20 cache RAM sizing.

SystemDesignQPSArchitectureScaling
Cloud & AWS →

Cloud & AWS Cost Calculator

Model realistic monthly and annual AWS cloud infrastructure budgets for Compute (EC2), RDS Databases, Redis Caches, S3 Storage, and Bandwidth Egress.

AWSCloudCostDevOpsFinOps
Containers →

Dockerfile & Compose Generator

Generate hardened, multi-stage production Dockerfiles for Node.js, Go, Python, and Rust with unprivileged non-root users and companion docker-compose.yml files.

DockerContainersDevOpsSecurity
Web Crypto →

Encoder, Decoder & Hash Suite

Pure client-side Base64/Base64URL encoder, URL percent encoder, Hex converter, and SHA-256 / SHA-512 / HMAC cryptographic digest generator.

Base64SHA-256HMACCryptoHex
Pricing →

LLM Cost Calculator

Interactive token pricing matrix for OpenAI, Anthropic, Google Gemini, DeepSeek, and open-source models. Calculate cost per request, monthly bill estimates, and prompt caching savings.

AILLMCostTokens