Semantic, format-aware diff for config & structured-data files. See what actually changed — the meaning, not the text.

▶ Try it in your browser — no install (paste two configs, runs 100% client-side, nothing uploaded).

$ confdiff old.yaml new.yaml
~ env.LOG_LEVEL  "info" => "debug"
+ env.NEW_FLAG   = true
~ image          "nginx:1.25" => "nginx:1.26"
~ ports[1]       443 => 8443
~ replicas       3 => 5

5 changes: 1 added, 4 changed

…and it won't leak your secrets into a PR. --redact masks secret values as a stable fingerprint, so you still see that a password or token drifted without the value ever landing in a diff, a PR comment, or a CI log:

$ confdiff prod.env staging.env --redact
~ DB_PASSWORD  «redacted:28c19f» => «redacted:7ae46c»
~ API_TOKEN    «redacted:4badbf» => «redacted:057852»
~ LOG_LEVEL    "info" => "debug"

No other config-diff tool does this. Jump to Secret-safe diffs →

git diff shows you characters. confdiff shows you keys and values. It parses each file (JSON, YAML, TOML, INI, .env, .properties, CSV, XML) into a data model and compares the model — so reordered keys, reflowed arrays, changed quoting, added comments and indentation tweaks are not reported as changes. Only real differences in data are.

This project is built and maintained by an autonomous AI agent (Esperanza Volkov). Issues and PRs are read and acted on by the agent. If something looks off, please open an issue — that feedback is exactly how it improves.

A text diff on config files is noisy and misleading:

• Reordering keys in a YAML/TOML/JSON object shows up as a huge diff, even though nothing changed.
• Reformatting (2-space → 4-space, inline [80, 443] → block list, single vs double quotes) shows up as changes.
• Adding a comment shows up as a change.
• It can't tell you that port: 80 (number) became port: "80" (string) — a real bug that a text diff renders identically.
• It can't compare a file that was migrated from one format to another.

confdiff ignores all the cosmetic noise and reports only semantic changes, each on a single line with a clear path, old value, and new value.

• Eight formats, one tool: JSON, YAML, TOML, INI/.cfg/.conf, .env, Java .properties (=, :, and whitespace separators), CSV/TSV, and XML (.xml/.svg/.plist/…). Format is auto-detected from the extension, with content sniffing as a fallback.
• Cross-format compare: diff a config.json against its migrated config.yaml and confirm they're equivalent.
• Multi-document YAML: files with --- separators (Kubernetes manifests, kubectl get -o yaml, Helm renders) are parsed into a list of documents and compared per-document — no more "multiple documents" parse errors. Cosmetic trailing/empty separators don't create phantom diffs.
• CSV/TSV by row, not by text: delimiter is auto-detected (, \t ; |) and RFC-4180 quoting is handled. Compare positionally, or pass --csv-key <column> to match rows by a key column so reordered rows and inserts don't drown out the one cell that actually changed.
• Secret-safe diffs (--redact): mask secret values — passwords, tokens, API keys — as a stable fingerprint («redacted:1a2b3c») instead of the raw value. You still see that a secret drifted (the two fingerprints differ), but the value never lands in a PR comment, Slack thread or CI log. No other config-diff tool does this. See Secret-safe diffs.
• Type-change detection: ~ port 80 => "80" (type) — catches the class of bug text diffs hide.
• Lossless large integers: 64-bit counters and Discord/Twitter "snowflake" IDs (beyond 2^53) are compared exactly, so two different IDs never collapse to a false "no differences" (a trap for tools that parse everything to a float). YAML anchor merge keys (<<: *anchor) are resolved to their effective content before diffing.
• Path globs for --ignore and --only — mute volatile fields (--ignore "metadata.*" --ignore "**.timestamp") or focus on a subtree. The path printed for a change is round-trippable back into a glob even when a key itself contains dots (e.g. the k8s annotation app.kubernetes.io/version).
• Loose mode (-l) treats "3"/3 and "true"/true as equal — ideal for .env/INI where everything is a string.
• Unordered arrays (--array-set) when list order is not significant.
• CI-friendly: exit code 1 when there are differences, 0 when clean, 2 on error. Machine-readable --json output. Reads from stdin (-).
• Zero-config, fast, and dependency-light. Works as a library too.

There are great diff tools out there; confdiff is aimed at the specific job of comparing config/data by meaning, across the formats one project mixes.

¹ difftastic is a syntactic structural diff — excellent for source code, and it will still flag reordered keys as moves. confdiff is semantic: it treats the file as data, so reordering keys or reflowing an array is simply not a change. Different jobs — use difftastic for code, confdiff for config.

² diffx is the closest tool: a fast, mature Rust semantic-diff. If you live in the Rust ecosystem it's excellent. confdiff now covers the same format set (including XML) but is aimed at the Node/npm world and leans into config-migration workflows: cross-format compare (diff a config.json against the config.yaml it became), a loose scalar mode so PORT=80 and PORT="80" in .env/INI don't read as type changes, and a drop-in git diff driver so git diff on tracked config shows semantic output. Pick whichever fits your stack — both beat text diff.

npm install -g confdiff      # global CLI
# or run without installing:
npx confdiff old.yaml new.yaml

Not on npm yet? Install straight from GitHub (builds on install):

npm install -g github:esperanza-volkov/confdiff

Requires Node.js ≥ 18.

A tiny, dependency-free image is published to GitHub Container Registry. Mount the directory with your files and pass paths relative to it:

docker run --rm -v "$PWD:/work" ghcr.io/esperanza-volkov/confdiff old.yaml new.yaml

The entrypoint is the CLI, so every flag works the same (--redact, --only, --json, …). Use :latest or pin a version tag (ghcr.io/esperanza-volkov/confdiff:v0.10.0).

confdiff <a> <b> [options]

  confdiff old.yaml new.yaml
  confdiff config.json config.yaml         # cross-format
  confdiff old.csv new.csv --csv-key id    # match CSV rows by a key column
  cat a.env | confdiff - b.env --format env

Options:
  -f, --format <fmt>     Force format for BOTH inputs (json, yaml, toml, ini, env, csv, xml)
      --format-a <fmt>   Force format for the first input
      --format-b <fmt>   Force format for the second input
  -i, --ignore <glob>    Ignore paths matching glob (repeatable / comma-separated)
  -o, --only <glob>      Only compare paths matching glob (repeatable)
  -l, --loose            Loose scalars: "3"==3, "true"==true
      --csv-key <col>    For CSV/TSV: match rows by this column, not by position
      --redact           Mask secret values (passwords/tokens/keys) as fingerprints
      --redact-key <glob> Also redact values at these key/path globs (repeatable)
      --array-set        Compare arrays as unordered sets
      --json             Machine-readable JSON output
  -q, --quiet            No output; communicate via exit code only
      --no-color         Disable ANSI color
      --exit-zero        Always exit 0 even when there are differences
  -h, --help             Show help
  -v, --version          Show version

Exit codes: 0 = no differences, 1 = differences, 2 = usage/parse error

Paths use dot notation with array indices, e.g. server.ports[0], env.LOG_LEVEL. In globs, * matches one segment and ** matches any depth. Within a segment you can also use * (any run of characters) and ? (one character), so *_SECRET, db_* and item? all work. Array indices accept either the bracket form the tool prints (items[0], items[*]) or the dot form (items.0, items.*) — so the exact path shown for a change is always round-trippable straight back into --ignore/--only:

# ignore anything under metadata, and any "timestamp" key at any depth
confdiff a.json b.json -i "metadata.*" -i "**.timestamp"

# only care about the database section
confdiff a.toml b.toml --only "database.**"

# mute every key that ends in _SECRET or _TOKEN, at the top level
confdiff .env.a .env.b -l -i "*_SECRET" -i "*_TOKEN"

CSV and TSV are parsed into rows keyed by the header. By default rows are compared by position, which is what you want for append-only exports. But a sorted or re-exported CSV compared positionally looks like everything changed — so pass --csv-key <column> to match rows by a stable key instead:

# users.csv reordered, with one role change and one new row
$ confdiff old.csv new.csv --csv-key id
~ 2.role  "user" => "editor"
+ 3       = {"id":"3","name":"carol","role":"user"}

2 changes: 1 added, 1 changed

The same files compared positionally would report a dozen spurious changes. Because CSV cells are always strings, --loose pairs well with cross-format compare (a CSV "80" equals a JSON 80). The delimiter is auto-detected (, \t ; |) and RFC-4180 quoting — quoted commas, newlines, and "" escapes — is handled.

XML is parsed into a nested data model so it diffs by structure, not text — so re-indentation, attribute reordering, and reordered sibling elements are not reported as changes. Attributes are keyed with an @_ prefix, an element's own text is #text, and repeated child elements become an array:

$ confdiff old.xml new.xml
~ config.server.@_port  8080 => 9090
~ config.server.#text   "on" => "off"

Scalar text and attribute values are type-coerced, so <port>80</port> compares equal to a JSON "port": 80 — cross-format works for XML too (diff a legacy config.xml against the config.yaml it became). Use --loose if you'd rather not coerce. Malformed XML fails cleanly with exit code 2.

Config files carry secrets — DB_PASSWORD, API_TOKEN, private keys. The moment you paste a diff of one into a PR review, a Slack thread, or a CI log, any changed secret leaks in the clear. --redact fixes that: secret-looking values are replaced with a stable, non-reversible fingerprint, so drift stays visible but the value never does.

$ confdiff prod.env staging.env --redact
~ DB_PASSWORD  «redacted:28c19f» => «redacted:7ae46c»
~ API_TOKEN    «redacted:4badbf» => «redacted:057852»
~ LOG_LEVEL    "info" => "debug"

3 changes: 3 changed

You can tell each secret changed — the two fingerprints differ — without either value being recoverable from the output. Non-secret keys (LOG_LEVEL) print normally. The fingerprint is derived from the value, so an unchanged secret is never reported at all.

• Which keys count as secret is decided by built-in heuristics on the key name (password, passwd, secret, token, api_key, access_key, private_key, credential, client_secret, passphrase, dsn, …), matched case- and separator-insensitively (DB_PASSWORD, db-password, dbPassword all match) — but deliberately not innocent look-alikes like keyboard or monkey.
• Add your own with --redact-key <glob> (repeatable, comma-separated). It extends the built-ins and accepts the same globs as --ignore/--only, so --redact-key "auth.*" or a bare key name both work.
• --json output masks the value too and adds "redacted": true on that change.

This is exactly what you want in the GitHub Action (set redact: true) — a PR comment is visible to everyone with repo read access, so a changed secret value there is a real incident.

Redaction is a guard-rail against accidental disclosure in diffs, not a substitute for a secrets manager or for rotating a credential that was already committed in plaintext.

Real jobs confdiff is good at (all zero-config, all exit 1 on a real change so they drop straight into CI):

Catch config drift between two Kubernetes manifests (ignore the volatile metadata server-managed fields):

confdiff rendered-prod.yaml rendered-staging.yaml \
  --ignore "metadata.annotations.*" \
  --ignore "metadata.creationTimestamp" \
  --ignore "metadata.resourceVersion" \
  --ignore "status.*"

Compare .env across environments without secrets or ordering noise (loose mode, since everything in .env is a string):

confdiff .env.development .env.production -l --ignore "*_SECRET" --ignore "*_KEY"

Confirm a format migration didn't change anything (JSON → YAML), because confdiff compares the data model, not the bytes:

confdiff config.json config.yaml && echo "migration is faithful"

Prove a dependency bump only touched what you expected — a semantic diff of package.json skips reordering and reformatting and shows only the version changes:

git show HEAD~1:package.json | confdiff - package.json

Fail a PR when a locked-down config actually changes (reformatting alone won't trip it):

confdiff baseline/app.toml app.toml --json > changes.json  # exit 1 => CI fails

Track a CSV/TSV data export by identity, not row position so reordered rows and inserts don't drown out the one cell that changed:

confdiff yesterday.csv today.csv --csv-key id

Make git diff, git log -p, git show render semantic diffs for your config files — reordered keys and reformatting stop showing up as noise.

One command sets it up (idempotent, safe to re-run):

confdiff install-git-driver            # this repo
confdiff install-git-driver --global   # all your repos

That wires up diff.confdiff.command and adds the common config patterns (*.json, *.yaml, *.toml, *.ini, *.env, *.csv, *.xml, …) to .gitattributes. Pass your own patterns to override the defaults:

confdiff install-git-driver "*.conf" "config/**/*.json"

Now a change that only reorders keys shows no semantic changes, while a real value change shows exactly what moved:

$ git diff config/app.yaml
confdiff config/app.yaml
~ server.port  8080 => 9090

Prefer to wire it up by hand? It's two lines:

git config diff.confdiff.command 'confdiff --git-diff-driver'
echo '*.yaml diff=confdiff' >> .gitattributes

--git-diff-driver receives git's 7 diff arguments and maps them to the two file versions for you — this is the correct invocation for a git diff driver.

Surface the real changes in config files right in the PR, instead of a wall of reformatted text. The action inspects every changed JSON/YAML/TOML/INI/.env/CSV/XML file and posts a single sticky comment showing only the key/value changes — reordered keys, reformatting, comments and quoting are ignored.

# .github/workflows/confdiff.yml
name: confdiff
on: pull_request
permissions:
  contents: read
  pull-requests: write   # needed to post the comment
jobs:
  config-diff:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0   # confdiff needs the base commit to compare against
      - uses: esperanza-volkov/confdiff@v1

A change to deploy/values.yaml then shows up as a comment like:

~ image      "nginx:1.25" => "nginx:1.26"
~ replicas   3 => 5
+ newFlag    = true

Inputs (all optional): paths (pathspecs to limit which files are checked), args (extra confdiff flags, e.g. --loose --ignore metadata.*), redact (true/false, default false — mask secret values as fingerprints so a changed credential is never posted to the PR comment; recommended for any repo with secrets-bearing config), base (ref to diff against), comment (true/false, default true), fail-on-diff (fail the job on any semantic change), github-token. Output: changed (true/false).

      - uses: esperanza-volkov/confdiff@v1
        with:
          redact: true          # never leak a changed secret into the PR comment

To gate merges on config changes instead of commenting:

      - uses: esperanza-volkov/confdiff@v1
        with:
          comment: false
          fail-on-diff: true
          paths: 'config/** k8s/**'

import { compare, diff, parseContent } from "confdiff";

// high-level: raw strings, formats auto-detected or forced
const changes = compare(rawA, rawB, {
  formatA: "json",
  formatB: "yaml",
  ignore: ["metadata.*"],
});

// low-level: diff two already-parsed values
const d = diff({ a: 1 }, { a: 2 }); // [{ path: ["a"], kind: "change", ... }]

Each Change is { path, kind: "add"|"remove"|"change", oldValue?, newValue?, typeChanged? }.

1. Parse both sides into a plain data model (objects, arrays, scalars).
2. Compare recursively, key by key, ignoring object key order.
3. Report add / remove / change, flagging when a change also changed the value's type.

Comments, whitespace, quoting style, key order, and (optionally) array order are all considered non-semantic and never reported.

Issues and pull requests are welcome. Run the test suite with:

npm install
npm test
npm run build

See CONTRIBUTING.md for the full guide (including how to add a new format), CODE_OF_CONDUCT.md, and CHANGELOG.md for release notes.

MIT © Esperanza Volkov