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ENV File Validator

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What This Tool Does

ENV File Validator is built for deterministic developer and agent workflows.

Validate .env files against .env.example — catch missing variables, empty values, and type mismatches.

Use How to Use for execution steps and FAQ for constraints, policies, and edge cases.

Last updated:

This tool is provided as-is for convenience. Output should be verified before use in any production or critical context.

Programmatic Access

ENV File Validator is also callable as a free HTTP JSON API at https://aidevhub.io/api/env-file-validator/ — GET with query parameters or POST with a JSON body, no authentication, CORS enabled, 50 requests/day per IP. Responses return { ok, tool, result, meta }. 

curl -s -X POST https://aidevhub.io/api/env-file-validator/ \
  -H "Content-Type: application/json" \
  -d '{"content":"API_KEY=abc123\nDEBUG=true\nPORT=3000"}'

Machine-readable contract: /api/tool/env-file-validator.json All API endpoints: /agents/ LLM site index: /llms.txt

Agent Invocation

Best Path For Builders

Dedicated API endpoint

Deterministic outputs, machine-safe contracts, and production-ready examples.

Dedicated API

https://aidevhub.io/api/env-file-validator/

OpenAPI: https://aidevhub.io/api/openapi.yaml

GET /api/env-file-validator/ GET env-file-validator
POST /api/env-file-validator/ POST env-file-validator

Unified Runtime API

https://aidevhub.io/api/tools/run/?toolId=env-file-validator&a=...

GET and POST are supported at /api/tools/run/ with identical validation and limits.

Limit: 30 req / 60s, input max 256 KB.

How to Use ENV File Validator

  1. 1

    Paste .env and .env.example in two panels

    Left: paste your .env (current config). Right: paste .env.example (template). Validator auto-detects variables and compares them immediately.

  2. 2

    Review validation results

    See summary cards: Valid, Missing, Extra, Empty, Type Issues. Each shows count and color (green=ok, red=error). Detailed list below shows exact problem variables.

  3. 3

    Check for missing or extra variables

    Red 'MISSING' label: key exists in template but not in your .env (will cause undefined errors). Orange 'EXTRA' label: key in your .env but not in template (undocumented).

  4. 4

    Enable type checking for validation

    Check 'Type checking' checkbox to detect mismatches (e.g., PORT should be number, not string). View inferred types in Variable Overview table.

  5. 5

    Copy validation report or fix manually

    Click 'Copy Report' to share results with team. Fix issues: add missing vars, remove extra vars, fill empty values. Revalidate until all clear.

Frequently Asked Questions

What is the ENV File Validator?
It validates your .env file against a .env.example template, catching missing variables, empty values, undocumented extras, and type mismatches before they cause runtime errors in production.
How do I use the ENV File Validator?
Paste your .env file on the left and your .env.example template on the right. The tool instantly shows a color-coded report of all issues: missing variables (red), undocumented extras (amber), empty values (orange), and type mismatches (blue).
Is this tool free?
Yes, Free to use with no signup. All validation happens in your browser — your environment variables never leave your device.
Does this tool store or send my data?
No. All processing happens entirely in your browser. Your .env contents are not sent to external servers. This is critical since .env files often contain secrets and API keys.
How to prevent missing env vars in production?
Use this tool in your CI/CD pipeline by validating .env against .env.example before deployment. Locally, paste both files here to catch issues before they become production KeyErrors. Enable type checking to also catch format mismatches like strings where URLs are expected.