envsync-le-mcp

Useful? A star or rating is how other developers find it — ★ GitHub · ★ Open VSX · ★ Marketplace

What it does

EnvSync-LE compares the variable names across the .env files in your workspace and tells you which files are missing which keys. It never reads or compares values, and it never modifies your files. Works in VS Code and in VS Code–based editors like Cursor and VSCodium (installable from Open VSX).

• Automatic checks — a debounced sync check runs whenever a watched .env file changes

• Status bar counter — the current issue count, one click away from the full report

• Markdown report — Show Details lists every missing key per file

• Three comparison modes — auto (union of all keys), manual (only the files you list), template (validate everything against one reference file; also reports keys a file has that the template lacks)

• Ignore list — temporarily exclude files (e.g. .env.example) from checking

Related MCP server: diff-checker

Install

Use it from an AI agent

The same engine runs as an MCP server, so an agent can call it directly instead of you running a command.

compare_env_files(files[], mode?, templatePath?, caseSensitive?, maxResults?)

Takes file contents directly and reports which keys are missing from which file. Only key names are returned, never values — a dotenv file is where credentials live and the answer does not need them.

The server takes content and returns data — it reads no files and makes no network requests of its own. Published as envsync-le-mcp on npm and as io.github.nolindnaidoo/envsync-le in the MCP registry.

Most hosts read a JSON config. Add one entry:

{
  "mcpServers": {
    "envsync-le": {
      "command": "npx",
      "args": ["-y", "envsync-le-mcp"]
    }
  }
}

-y skips the install prompt on first run. Pin a version if you would rather not track releases — envsync-le-mcp@2.3.0.

Prefer not to go through npx on every launch? Install it once and point at the binary instead:

npm install -g envsync-le-mcp

{
  "mcpServers": {
    "envsync-le": { "command": "envsync-le-mcp" }
  }
}

It speaks MCP over stdio and needs no environment variables, no API key and no configuration of its own. To check it before wiring it into anything:

echo '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' | npx -y envsync-le-mcp

That prints the tool list and exits — if you see compare_env_files, the server works.

File classification

Classification is segment-based on the basename — app.device.env is not "development", and Windows paths classify correctly.

The CLI

The same comparison runs from a terminal or a CI step: a Rust CLI in crate/, sharing one corpus with the extension — crate/fixtures/ — so the two can never read a dotenv file differently. Install it from npm with npm install -g envsync-le (or run it with npx envsync-le) or from crates.io with cargo install envsync-le. Both install the same command and are held to the same output byte for byte.

envsync-le .                            # have these environments drifted? JSON on stdout when piped
envsync-le --template .env.example .    # will this deploy break?
envsync-le mcp                          # the same comparison over MCP on stdio

Install it from npm (envsync-le) or from crates.io (envsync-le). Both install the same envsync-le command.

npm install -g envsync-le   # or run it once: npx envsync-le
cargo install envsync-le

.env: missing STRIPE_KEY, SENTRY_DSN (in .env.example)
.env.production: missing SENTRY_DSN (in .env.example)
out of sync — 2 files with mismatches across 3 files

The exit code is the product — 0 in sync, 1 out of sync, 2 malformed question. Finding no dotenv files at all is 0: there is nothing to be out of sync with. Unlike the extractors in this family there is no list to pipe onward; the number is the answer.

It never reads a value. Only key names are parsed, compared or reported, and three separate checks enforce that rather than a promise.

Commands

No command is bound to a key by default. Give any of them one under Keyboard Shortcuts in the editor.

Settings

Parsing notes

• Keys must match [A-Za-z_][A-Za-z0-9_.-]*, so dotted names such as spring.datasource.url count; anything else left of = is reported as a parse error for that line (the rest of the file still counts).

• export KEY=value is accepted; duplicate keys count once.

• Values quoted with ", ', or ` may span multiple lines; an unterminated quote is reported as an error.

• In auto mode the reference is the union of all keys, so "extra keys" only exist in template mode.

Languages

Twelve languages besides English:

German · Spanish · French · Indonesian · Italian · Japanese · Korean · Portuguese (Brazil) · Russian · Ukrainian · Vietnamese · Chinese (Simplified)

Both halves are covered — the manifest (command titles, setting names and descriptions) and everything shown while the extension runs (notifications, the status bar, quick-picks and prompts, and the headings of the report). The help page is written in English. The extension follows VS Code's display language, so it matches whatever the editor is already set to; no setting of its own.

Privacy & security

• No network access. The extension never sends data anywhere. The telemetryEnabled setting only writes events to a local Output Channel you can inspect (envsync-le).

• Values are never read, displayed, or logged — only key names are compared.

• The MCP server returns key names, never values. A dotenv file is where credentials live, so the server reports which keys are missing or extra and nothing about what they contain. It takes file contents as an argument rather than paths, so it reads no files and makes no network calls; the bundle gate asserts a known value is absent from its response.

• Error notifications redact home directories and credential-shaped fragments.

• One rating prompt, at most twice. On the 3rd successful use the extension asks once whether you would rate it, and once more on the 20th if you chose Later or dismissed it. Don't Ask Again ends it. Setting notificationLevel to important or silent yourself turns it off. The counts are kept in VS Code's extension storage and nothing is sent anywhere; Rate opens the listing you installed from — the VS Code Marketplace or Open VSX — in your browser.

Documentation

Performance

Median of 7 runs after warmup, on Apple M5 Pro, 24 GB RAM, Node 24.3.0. Inputs are generated by scripts/benchmark.ts rather than checked in, so the sizes above are exactly what was measured. Reproduce with bun run benchmark.

These are machine-specific and are not asserted in CI — a benchmark that gates a build only tells you how busy the runner was.

Testing

354 test cases across 28 files, plus an integration suite that runs in a real VS Code extension host and an end-to-end test that installs the built .vsix into a clean profile.

Generated from a real run — coverage/coverage-summary.json and coverage/test-results.json — by scripts/coverage-readme.js, and bun run coverage:readme:check says whether it has drifted since. Reproduce with bun run test:coverage, and the case count is the one vitest prints.

More from the LE family

Sixteen single-purpose tools for the work in front of every model. Each ships a Rust CLI and an MCP server. One page: letools.dev

Get it out

• String-LE — Extract every string in a codebase, so a person can read them

• Numbers-LE — Extract every hardcoded number in a codebase, so a person can check them

• Units-LE — Extract every quantity with its unit, normalized, and refuse the ambiguous ones by name

• Dates-LE — Extract every date and timestamp, and the exact instant each one resolves to

• IDs-LE — Extract every UUID, ULID, NanoID, ObjectId and Snowflake, and decode the time inside

• IPs-LE — Extract every IP address, CIDR block and MAC, normalized and classified by scope

• URLs-LE — Extract every URL in a codebase, with its protocol and exact position

• Paths-LE — Extract every file path in a codebase, and say whether it still points at anything

• Colors-LE — Extract every color in a codebase, and say which ones are not in your palette

Check it

• Regex-LE — Find every regex in a codebase, and report which can be driven into catastrophic backtracking

• Versions-LE — Find where one dependency is constrained differently across a repository's manifests

• i18n-LE — Identify the i18n library a project uses, then audit its catalogs by that library's rules

• Scrape-LE — Check whether a page is scrapeable before the scraper is written, and say when it cannot tell

Guard it

• Secrets-LE — Find hardcoded credentials in a codebase, and never print one into the report

• EnvSync-LE — Compare the dotenv files in a tree, and say which keys are missing from which

• Unicode-LE — Find the Unicode that hides meaning — bidi controls, invisibles, homoglyphs, mixed scripts

Each stands on its own: no shared crate, no published core. Where two of them agree, it is because the same answer was right twice.

Contact — nolindnaidoo.com · GitHub · LinkedIn

Also by nolindnaidoo

Rust — pixelcoords and pixelactions are one loop: pixelcoords answers where, pixelactions acts there. Their own tools, their own voice — not part of the LE family.

• pixelcoords — Freeze your screen, mark regions, get pixel-exact coordinates and crops pixelcoords.dev · crates.io · docs.rs

• pixelactions — Consume human-verified coordinates, perform the interaction, confirm it landed pixelactions.dev · crates.io · docs.rs

License

MIT © nolindnaidoo