JSON patch apply

json-patch-apply · version 1.0.0 · JSON & JSONL · free, no key needed

Apply an RFC 6902 JSON Patch atomically; returns the document or the failing operation index and pointer.

Use when you need to: apply a JSON patch atomically · update a JSON document with patch operations · run RFC 6902 operations.

Decide before calling

Read the versioned contract and the supported scope below. Reuse json-patch-apply@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use json-patch-apply@1.0.0 for apply a JSON patch atomically. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

apply a JSON patch atomically
update a JSON document with patch operations
run RFC 6902 operations
apply add remove replace move copy and test
find which JSON patch operation failed
patch JSON without partial changes

Not supported

generate a patch between documents
modify files on disk

Behavior

Unrecognized operation members are ignored (RFC 6902 section 4); only the members defined for that op are interpreted. Removing the document root returns applied:false and reason root_removal_unsupported, preserving the original document: this JSON-result API cannot represent absence of a document.
Implements RFC 6902 (April 2013), Sections 4 and 5, with JSON Pointer syntax from RFC 6901 (April 2013), Sections 3 and 4.
Inputs are JSON values; object keys are compared exactly and arrays are ordered. Processing is synchronous and deterministic.
Limits are checked before or during bounded traversal; no network, filesystem, clock, locale, or randomness is used.

Input

document (any JSON value, required)
patch (array of object, required): max items 128

Output

standard_version (constant "RFC 6902 (April 2013); RFC 6901 (April 2013)", required)
applied (boolean, required)
document (any JSON value, required)
failed_index (integer, optional): min 0; max 127
failed_pointer (string, optional)
reason (string, optional)

Limits

max input bytes: 65536
max operations: 128
max depth: 32
max output bytes: 131072
max iterations: 4096

Example

Request input:

{
  "document": {
    "a": 1
  },
  "patch": [
    {
      "op": "replace",
      "path": "/a",
      "value": 2
    }
  ]
}

Response:

{
  "result": {
    "standard_version": "RFC 6902 (April 2013); RFC 6901 (April 2013)",
    "applied": true,
    "document": {
      "a": 2
    }
  }
}

How to call it

MCP

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

{
  "id": "json-patch-apply",
  "version": "1.0.0",
  "input": {
    "document": {
      "a": 1
    },
    "patch": [
      {
        "op": "replace",
        "path": "/a",
        "value": 2
      }
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/json-patch-apply/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"document":{"a":1},"patch":[{"op":"replace","path":"/a","value":2}]}'

The machine-readable contract is at /v1/tools/json-patch-apply/versions/1.0.0.

CLI

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

Get the client at /clients/cli/.

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JSON patch diff: Generate a deterministic RFC 6902 patch from two JSON documents; returns the ordered patch operations.
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JSON schema instance locate: Resolve RFC 6901 instance locations (string or URI fragment) from schema errors to values, or say why they fail.
JSON schema output validate: Validate JSON (e.g. LLM output) against a Draft 2020-12 schema subset; returns spec output units with JSON Pointers.
JSON fence extract: List Markdown fenced code blocks (CommonMark 0.31.2) with exact spans, unwrapped content and an RFC 8259 JSON check.