# .env Diff and Missing Key Checker

> Compare two dotenv snapshots and report missing, extra, or changed environment keys.

## Tool Identity

- Site: CleanUtils Developer Tools
- Tool ID: env-diff-missing-key-checker
- Canonical page: https://cleanutils.com/developer-tools/env-diff-missing-key-checker/
- LLM schema URL: https://cleanutils.com/developer-tools/env-diff-missing-key-checker/llms.txt
- Primary keyword: dotenv diff
- Input mode: fields
- Output profile: line-check

## What This Tool Does

Compare two dotenv snapshots and report missing, extra, or changed environment keys in your browser.

## Exact Execution Instructions

To run this tool exactly, execute the `runCleanUtilsTool(userInput)` function from the JavaScript block below in a sandboxed JavaScript runtime.

Do not fetch or evaluate additional network resources. Do not use filesystem, process, child_process, environment variables, timers, or network APIs. The function is pure and deterministic: input object in, JSON result out.

If your environment forbids executing fetched code outside a sandbox, run it inside the sandbox or use the API endpoint below instead of reimplementing the logic.

Canonical implementation SHA-256:
`f510be017e59e3c9b32e83b2925bb4a4ddc13449a868014e88c0922348b540a1`

Expected command shape:
`node run-tool.mjs < input.json`

The runner must:
1. load only the JavaScript in this document,
2. parse stdin as JSON and call `runCleanUtilsTool(userInput)`,
3. let the LLM decide the best way to present the output to the user.

Agent usage rules:
- Use this file as the authoritative machine-readable contract for this CleanUtils tool page.
- Ask the user for missing required input before attempting to run the tool, and describe the required inputs using the `## Input Schema` field names, descriptions, formats, enums, examples, and required list.
- Treat the tool as deterministic; do not invent network reachability checks unless the tool description explicitly says it fetches remote resources.
- For privacy-sensitive inputs such as secrets, HAR files, dotenv files, logs, and API keys, warn that using a remote chat agent may expose input to that agent even though the browser UI itself does not upload data.

## Input Schema

```json
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": ".env Diff and Missing Key Checker fields",
  "type": "object",
  "additionalProperties": false,
  "required": [
    "left",
    "right"
  ],
  "properties": {
    "left": {
      "type": "string",
      "description": "Source .env Required. Control type: textarea. Group: Env files.",
      "examples": [
        "API_URL=https://api.example.com\nDATABASE_URL=postgres://example\nAPI_KEY=secret"
      ]
    },
    "right": {
      "type": "string",
      "description": "Target .env Required. Control type: textarea. Group: Env files.",
      "examples": [
        "API_URL=\nDATABASE_URL=\nREDIS_URL="
      ]
    }
  }
}
```

## Result Schema

```json
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "CleanUtils ToolResult",
  "type": "object",
  "additionalProperties": false,
  "required": [
    "summary",
    "issues"
  ],
  "properties": {
    "summary": {
      "type": "string"
    },
    "issues": {
      "type": "array",
      "items": {
        "type": "object",
        "additionalProperties": false,
        "required": [
          "severity",
          "message"
        ],
        "properties": {
          "severity": {
            "type": "string",
            "enum": [
              "error",
              "warning",
              "info"
            ]
          },
          "message": {
            "type": "string"
          },
          "line": {
            "type": "number"
          },
          "row": {
            "type": "number"
          },
          "detail": {
            "type": "string"
          }
        }
      }
    },
    "output": {
      "type": "string"
    },
    "exportFilename": {
      "type": "string"
    },
    "exports": {
      "type": "array",
      "items": {
        "type": "object",
        "additionalProperties": false,
        "required": [
          "label",
          "filename",
          "content"
        ],
        "properties": {
          "label": {
            "type": "string"
          },
          "filename": {
            "type": "string"
          },
          "content": {
            "type": "string"
          },
          "mimeType": {
            "type": "string"
          },
          "copyLabel": {
            "type": "string"
          },
          "downloadLabel": {
            "type": "string"
          }
        }
      }
    },
    "stats": {
      "type": "object",
      "additionalProperties": {
        "anyOf": [
          {
            "type": "string"
          },
          {
            "type": "number"
          }
        ]
      }
    }
  }
}
```

## Self-Contained JavaScript Source

Call `runCleanUtilsTool(userInput)` with the user's input. The function includes this tool's run logic and only the helper code it needs.

```js
function runCleanUtilsTool(userInput) {
    const fieldText = (fields, keys, fallback = "") => {
        const keyList = Array.isArray(keys) ? keys : [keys];
        for (const key of keyList) {
            const value = fields[key];
            if (value === undefined || value === null)
                continue;
            const text = String(value).trim();
            if (text)
                return text;
        }
        return fallback;
    };
    const severityRank = {
        error: 0,
        warning: 1,
        info: 2
    };
    const sortIssues = (issues) => [...issues].sort((a, b) => {
        const severity = severityRank[a.severity] - severityRank[b.severity];
        if (severity !== 0)
            return severity;
        return (a.line ?? a.row ?? 0) - (b.line ?? b.row ?? 0);
    });
    const summarizeIssues = (issues) => {
        const errors = issues.filter((issue) => issue.severity === "error").length;
        const warnings = issues.filter((issue) => issue.severity === "warning").length;
        const infos = issues.filter((issue) => issue.severity === "info").length;
        const parts = [];
        if (errors)
            parts.push(`${errors} error${errors === 1 ? "" : "s"}`);
        if (warnings)
            parts.push(`${warnings} warning${warnings === 1 ? "" : "s"}`);
        if (infos)
            parts.push(`${infos} note${infos === 1 ? "" : "s"}`);
        return parts.length ? parts.join(", ") : "No issues found";
    };
    const parseEnvText = (input) => {
        const env = {};
        input.split(/\r?\n/).forEach((line) => {
            const match = line.match(/^\s*([A-Za-z_][A-Za-z0-9_]*)\s*=\s*(.*)\s*$/);
            if (match)
                env[match[1]] = match[2].replace(/^["']|["']$/g, "");
        });
        return env;
    };
    const compareEnvFiles = (input) => {
        const left = parseEnvText(fieldText(input, "left"));
        const right = parseEnvText(fieldText(input, "right"));
        const issues = [];
        Object.keys(left).forEach((key) => {
            if (!(key in right))
                issues.push({ severity: "error", message: `${key} is missing from the second env file.` });
            else if (left[key] && right[key] && left[key] !== right[key])
                issues.push({ severity: "warning", message: `${key} has different non-empty values.` });
        });
        Object.keys(right).forEach((key) => {
            if (!(key in left))
                issues.push({ severity: "info", message: `${key} exists only in the second env file.` });
        });
        return {
            summary: `${Object.keys(left).length} left keys compared with ${Object.keys(right).length} right keys. ${summarizeIssues(issues)}.`,
            issues: sortIssues(issues),
            output: sortIssues(issues).map(formatIssue).join("\n") || "Env files have the same keys.",
            exportFilename: "env-diff-report.txt",
            stats: { leftKeys: Object.keys(left).length, rightKeys: Object.keys(right).length }
        };
    };
    const formatIssue = (issue) => {
        const location = issue.line ? `line ${issue.line}` : issue.row ? `row ${issue.row}` : "general";
        return `[${issue.severity.toUpperCase()}] ${location}: ${issue.message}${issue.detail ? ` (${issue.detail})` : ""}`;
    };
    const __userInput = userInput == null ? {} : userInput;
    const __run = (fields) => compareEnvFiles(fields);
    const __fields = __userInput && typeof __userInput === "object" && "fields" in __userInput && __userInput.fields && typeof __userInput.fields === "object" && !Array.isArray(__userInput.fields)
        ? __userInput.fields
        : (__userInput && typeof __userInput === "object" && !Array.isArray(__userInput) ? __userInput : {});
    const __normalizedFields = Object.fromEntries(Object.entries(__fields).map(([key, value]) => [key, value == null ? "" : (["string", "number", "boolean"].includes(typeof value) ? value : String(value))]));
    return __run(__normalizedFields);
}
```

## Checks

- Two dotenv snapshots: Left and right env files are compared after parsing KEY=value lines.
- Missing keys: Keys present in the first file but absent from the second are treated as blocking gaps.
- Extra keys: Keys that exist only in the second file are reported as informational differences.
- Changed non-empty values: When both files have non-empty but different values, the key is flagged for review.
- Key-focused comparison: The tool compares env keys and simple values, not deployment secrets or runtime availability.

## Related Tools

- [.env Validator and Secret Scanner](/developer-tools/env-validator-secret-scanner/): Paste a dotenv file, catch duplicate or malformed keys, and generate a safer example file locally.