.env merge

env-merge · version 1.0.0 · Versions & config · free, no key needed

Overlay two dotenv-subset documents, replacing left values and appending right-only keys.

Use when you need to: env merge · merge env files · overlay env documents.

Supported

• env merge
• merge env files
• overlay env documents

Not supported

• merge more than two documents
• preserve comments
• variable expansion
• three-way merge
• read files

Behavior

• left and right are env texts parsed with the same rules as env-parse.
• The merge starts with left entries in left order. Right keys already present replace the value in place.
• Right-only keys are appended in right order after every left key.
• The output is the canonical stringify of the merged entries as text; comments are not preserved.
• Parsing the output yields the merged map.

Input

• left (string, required): max length 256000
• right (string, required): max length 256000

Output

• text (string, required): max length 256000

Limits

• max input bytes: 256000
• max lines: 5000
• max output bytes: 256000

Example

Request input:

{
  "left": "# base\nNAME=Ada\nNOTE=hi\nPORT=1\n",
  "right": "NOTE=\"hello world\"\nCITY=Tel_Aviv\n"
}

Response:

{
  "result": {
    "text": "NAME=Ada\nNOTE=\"hello world\"\nPORT=1\nCITY=Tel_Aviv\n"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "env-merge",
  "version": "1.0.0",
  "input": {
    "left": "# base\nNAME=Ada\nNOTE=hi\nPORT=1\n",
    "right": "NOTE=\"hello world\"\nCITY=Tel_Aviv\n"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/env-merge/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"left":"# base\nNAME=Ada\nNOTE=hi\nPORT=1\n","right":"NOTE=\"hello world\"\nCITY=Tel_Aviv\n"}'

The machine-readable contract is at /v1/tools/env-merge/versions/1.0.0.

CLI

node cli.mjs run env-merge 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• .env parse: Parse a strict dotenv-subset document into ordered key/value entries.
• .env stringify: Serialize unique env key/value entries to a canonical dotenv-subset document.
• SemVer compare: Compare two strict Semantic Versions by precedence.
• SemVer filter: Filter strict versions that satisfy a range, preserving original order and strings.
• SemVer satisfies: Test whether a strict version satisfies a semver range.
• SemVer sort: Sort strict valid Semantic Versions in ascending precedence order.