Developer Tools
Free tools for backend and API work
Ten focused, browser-based utilities for the everyday problems in Node.js, Next.js, PostgreSQL, and API development — JSON formatting, JWT inspection, connection strings, encoding, timestamps, cron schedules, UUIDs, .env checks, CORS configuration, and Nepal VAT math.
Popular tools
- Data formatting
JSON Formatter & Validator
Format, minify, and validate JSON with clear syntax-error locations.
- Security & tokens
JWT Decoder
Decode a JWT's header and payload and inspect standard claims locally.
- Database
PostgreSQL Connection URL Builder
Assemble a correctly encoded PostgreSQL or Prisma connection string.
- Date & time
Unix Timestamp Converter
Convert between Unix time, ISO 8601, and readable dates across time zones.
- Identifiers
UUID Generator
Generate cryptographically random UUID v4 values in bulk.
- Nepal business
Nepal VAT Calculator
Add or extract Nepal VAT from an amount, with NPR-formatted results.
All tools
10 of 10 tools
- Data formatting
JSON Formatter & Validator
Format, minify, and validate JSON with clear syntax-error locations.
- Security & tokens
JWT Decoder
Decode a JWT's header and payload and inspect standard claims locally.
- Database
PostgreSQL Connection URL Builder
Assemble a correctly encoded PostgreSQL or Prisma connection string.
- Encoding
Base64 Encoder & Decoder
Encode UTF-8 text to Base64 or Base64URL, and decode it back safely.
- Date & time
Unix Timestamp Converter
Convert between Unix time, ISO 8601, and readable dates across time zones.
- DevOps
Cron Expression Builder & Explainer
Build, validate, and plain-English explain a standard five-field cron expression.
- Identifiers
UUID Generator
Generate cryptographically random UUID v4 values in bulk.
- Configuration
Environment File Validator
Check .env content for duplicate keys, malformed lines, and missing values.
- API development
CORS Configuration Generator
Generate framework-specific CORS configuration from your allowed origins and methods.
- Nepal business
Nepal VAT Calculator
Add or extract Nepal VAT from an amount, with NPR-formatted results.
How these tools handle your data
Every tool runs entirely in your browser. Nothing you paste or generate — JSON, tokens, credentials, amounts — is uploaded, transmitted to a server, or stored. Analytics, when enabled, only ever records that a tool page was viewed or that an action like "format" or "generate" succeeded — never your input, output, or results.
Related writing
- JWT authentication without mythology — rotations, revocation, and session ergonomicsSymmetric versus asymmetric verification, JWKS fleets, leaky storage pitfalls, and when opaque cookies outperform bearer tokens.
- Hashing vs Encryption vs Encoding — The Differences Developers Must UnderstandA production-minded map of encoding, hashing, and encryption—salts, passwords, JWTs, Base64 myths, interview answers, and the mistakes reviewers catch.
- Database indexing beyond B-trees — selectivity, partial indexes, and write amplificationHow query planners pick indexes, when covering indexes beat heap fetches, and the operational cost every extra index hides.