JSON Inside JSON: Why Some Fields Are Strings Containing Their Own JSON, and How to Parse Them

A field in a database that contains the text "{\"name\":\"Alice\",\"age\":30}" isn't broken — it's JSON, stored as a string, inside a JSON document — and this "JSON inside JSON" pattern is extremely common in logging, GraphQL, and webhook payloads, requiring two separate parsing steps to get to the actual data

The previous articles on this site covered double-encoding causes, language-specific parsing edge cases, and JSON Patch/Pointer standards. This article addresses a related but distinct pattern: JSON values that are themselves strings containing JSON — not as an error, but as a deliberate, if sometimes confusing, design choice in several common systems.

Why "JSON containing a JSON string" happens deliberately

Logging systems: an application logs a structured event — {"timestamp": "...", "level": "info", "message": "User created", "payload": "{\"userId\":123,\"email\":\"...\"}"} — where the outer JSON represents the log entry itself (timestamp, level, message), and the payload field contains a separate JSON object, serialized as a string, representing the actual event data.

Why not just nest it as a regular JSON object ("payload": {"userId": 123, ...}, without the extra string-escaping)? Often because the logging system's schema defines payload as a generic "string" field — accepting any event-specific data as an opaque string, without the logging system itself needing to understand the structure of every possible event type. The application serializes its event-specific data to a JSON string; the logging system stores/indexes it as "just a string" (though many log-analysis platforms can additionally parse such string fields as JSON, when configured to do so).

GraphQL and webhook payloads: similarly, some APIs include a field whose value is "the raw JSON payload from [some other system]" — passed through as a string, without the receiving API needing to define a schema for every possible shape that payload might take.

The two-step parsing this requires

To get from the outer JSON to the actual, inner data:

1. Parse the outer JSON — standard JSON parsing, giving you an object where payload (or whatever the field is called) is a string value
2. Parse that string value as JSON, separately — a second, independent JSON-parsing operation, on the string's content

A common mistake: treating the outer-parsed object's payload field as if it were already a JSON object — data.payload.userId — when data.payload is, at this point, still a string ("{\"userId\":123,...}"), not an object — accessing .userId on a string doesn't work the way accessing it on an object does (in most languages, this would return undefined/null/an error, rather than 123).

The fix: JSON.parse(data.payload).userId (in JavaScript-like syntax) — or the equivalent two-step parse in whatever language is being used.

How to recognize this pattern when looking at raw JSON

Visually, a "string containing JSON" looks like: a JSON string value where the content itself contains {, }, ", :, , characters — but with the inner quotes escaped (\") because they're inside an outer JSON string.

{
  "event": "purchase",
  "details": "{\"item\":\"Widget\",\"price\":29.99}"
}

The \" sequences are the tell — a JSON object that was directly nested (not string-encoded) would use unescaped " characters for its own keys/values, because it would be a genuine nested object, not a string.

{
  "event": "purchase",
  "details": {"item": "Widget", "price": 29.99}
}

These two examples represent different data structures — the first has details as a string (requiring a second parse); the second has details as an object (no second parse needed, already directly accessible).

When this pattern becomes a problem: unnecessary stringification

The pattern described above is legitimate when there's a genuine reason for the "outer" schema to treat the inner data as opaque (the logging-system example).

But the same visual pattern — \"-escaped JSON-within-a-string — can also appear unnecessarily, as a bug — e.g., a backend that serializes an object to a JSON string, and then also includes that string as a value within a larger JSON structure that's itself serialized — effectively double-encoding the inner data as JSON, for no reason, when it could simply have been included as a nested object directly.

The distinction (legitimate vs bug) usually comes down to: does the receiving system actually need/want this data as an opaque string (logging, generic webhook relay) — or would it be more useful, with no downside, as a directly-nested object (in which case the string-encoding is unnecessary complexity, likely introduced by a serialization step that shouldn't have been applied)?

How to use the JSON Unescape & Cleaner tool on sadiqbd.com

1. Paste the outer JSON — if a field's value contains visible \" sequences forming what looks like another JSON structure, that field is a string containing JSON, requiring a second parse
2. Copy that field's string value (the content between the outer quotes, with \" representing literal " characters) and run it through this tool again — unescaping/parsing it as its own JSON document
3. For deeply-nested cases (a string containing JSON, which itself contains a string containing JSON, and so on) — repeat this process for each level — though more than two levels is unusual outside of specific logging/relay architectures

Frequently Asked Questions

Is there a way to make a JSON viewer automatically "see through" string-encoded JSON fields? Some JSON-viewing/log-analysis tools offer this as a feature — detecting fields whose string content looks like JSON, and offering to expand/parse them inline, without requiring a manual copy-paste-reparse cycle. Whether this site's tool offers automatic detection of such fields depends on the specific implementation — but the manual two-step process (described above) works universally, regardless of whether a specific tool offers automatic detection, and is useful to understand conceptually even when automatic detection is available, for cases the automatic detection doesn't catch.

Is the JSON Unescape & Cleaner tool free? Yes — completely free, no sign-up required.

Try the JSON Unescape & Cleaner free at sadiqbd.com — unescape and parse nested, string-encoded JSON instantly.