JSON to YAML Converter — Online & Private

How JSON to YAML conversion works

JSON to YAML Converter Online — No Upload runs JSON payloads through a deterministic, fully client-side pipeline and produces YAML output in a single pass — no round-trips, no queues, no waiting on someone else's server. Paste an array of objects (or a single object) into the input pane — nested objects are flattened with dot paths automatically. Press Run Conversion (or just pause typing — the studio parses as you go), and the generated output appears on the right with line numbers, syntax highlighting, and one-click copy or download.

JSON shape detection — arrays, objects, and flattening

The parser accepts the four shapes real JSON data arrives in: an array of objects (the canonical form — every API list endpoint), a single object (one row), an array of arrays (positional columns, first row as header), and an object of arrays (column name to values, the plotly/ dataframe encoding). No configuration is needed — the shape is detected structurally, and anything outside those forms is rejected with a precise message instead of a wrong answer.

Nested objects are flattened with dot paths — user.name becomes its own column named user.name — and array values serialize to their JSON text, so a nested API response converts without losing structure. Null becomes an empty cell, and numbers and booleans keep their native types into typed outputs. Headers are the union of keys in first-seen order, so records with missing fields convert with blanks rather than errors.

JSON to YAML: tree in, tree out

JSON and YAML are both tree formats, so this converter preserves structure instead of flattening it: nested objects become nested block mappings, arrays become block sequences, an array of objects becomes the list-of-mappings shape Ansible inventories, docker-compose fragments, and CI matrices expect, and a single object becomes a plain mapping document — not wrapped in a list — because that is the shape config files actually have. The only inputs that flatten are the two explicitly tabular JSON shapes (an array of arrays with its first row as a header, and an object of column arrays), which convert through the same table pipeline as the CSV and Excel paths — matching how every other converter on this site interprets them. The sibling tools follow the same rule by target: JSON to CSV and JSON to Excel flatten to rectangles because spreadsheets are rectangular, JSON to Apex turns the payload into a typed Salesforce wrapper class instead of another data format, while CSV to YAML and Excel to YAML share this page's block-style output — and the full conversion studio switches formats without losing your input.

Scalar translation is where naive JSON-to-YAML conversion corrupts data, because the two formats disagree about bare words: the JSON string "on" must be quoted in YAML or it loads as true, "8080" must be quoted or it loads as a number, and the string "null" must be quoted or it loads as nothing at all. The generator quotes exactly those strings and leaves safe ones bare; JSON numbers and booleans pass through unquoted because YAML reads them identically, and JSON null becomes YAML null — the honest translation of the value rather than an empty-string stand-in that changes the data model on load.

Block-style YAML with honest scalar quoting

The output is a block sequence of mappings — the YAML shape configuration files, docker-compose services, and Ansible inventories actually use, not flow-style JSON-in-YAML. Each row becomes a list item with one key per line, indented consistently, so the file diffs cleanly in code review and survives YAML linters that reject flow collections.

Scalar quoting is where YAML converters usually go wrong, and this one is deliberate: strings that would parse as something else — true/false, yes/no, on/off, null, numbers, or values containing colons and hashes — are emitted double-quoted, while safe strings stay bare and readable. Empty cells become "" rather than a bare nothing, because bare emptiness in YAML is null, not an empty string — the distinction that breaks naive converters' round-trips.

Private by architecture: your data never leaves the browser

Every stage of this conversion — parsing, type inference, and output generation — executes locally inside your browser's JavaScript engine. The input is never transmitted, logged, or stored: there is no upload endpoint, no queue, no telemetry, and no account to create. Files larger than 1MB are handed to a background Web Worker so the interface keeps animating at 60fps even on hundred-thousand-row imports, and the page keeps working offline once loaded because it is a fully static export.

That architecture makes the tool safe for the exports you would never paste into a random website: customer PII, financial line items, internal Salesforce extracts, and unreleased product data. Paste it, convert it, copy or download the result — and the bytes never moved from your machine.

Limits and practical tips

Inputs are capped at 15MB per file or paste — hundreds of thousands of rows in practice — purely as a browser-safety guard rather than a server policy, since there is no server involved at all. Processing is single-pass and deterministic: the same input with the same options always produces byte-identical output, which makes the generator safe to keep in CI pipelines and documentation. Paste the output into a YAML linter when targeting strict consumers — the quoting rules here favor correctness over minimalism.

How do I convert JSON to YAML?

Paste your JSON — an array of objects, a single object, an array of arrays, or an object of column arrays — pick YAML as the target, and press Run Conversion. The block-style YAML appears instantly with copy and download buttons, and the output regenerates automatically as you edit the input once it parses.

Is my JSON nesting preserved in the YAML output?

Yes. JSON and YAML are both tree formats, so object-shaped input converts structurally: nested objects stay nested block mappings, arrays become block sequences, an array of objects becomes a list of mappings, and a single object becomes a plain mapping document without a list wrapper. Only the two explicitly tabular shapes — an array of arrays (first row is the header) and an object of column arrays — convert through the table pipeline, the same interpretation every converter on this site applies to those shapes.

When does the converter quote YAML values?

Exactly when quoting is required for correctness: strings that would otherwise load as booleans or null (true/false, yes/no, on/off, null, ~), strings that look like numbers (8080, 1e5), and strings containing YAML indicators such as colons or hashes. JSON numbers and booleans pass through bare because YAML reads them identically, and safe strings stay bare so the file stays readable.

How are null and the empty string handled?

JSON null becomes YAML null — the honest translation of the value — while an empty JSON string becomes "" so the two survive a load round-trip as distinct values. That distinction is what breaks naive converters: leaving an empty string bare makes YAML load it as null, silently changing your data's types downstream.

Is my JSON uploaded to a server?

No. Parsing and YAML generation run entirely inside your browser — the bytes never leave your machine, nothing is logged, and there is no account. Inputs over 1MB are processed in a background Web Worker, which keeps the page responsive without moving any data off your machine.

Does the output use tabs or spaces, and which YAML version is it valid for?

Two-space block indentation, never tabs — the convention every YAML loader and yamllint's default rules expect. The output targets the YAML 1.2 core schema: block style only (flow syntax appears solely for explicit empty collections, as [] and {}), scalar quoting applied per the 1.2 resolution rules, and key order matching your JSON's key order so diffs track the source. PyYAML, Go's gopkg.in/yaml.v3, JavaScript's js-yaml, and Rust's serde_yaml all parse the result identically.

Can I convert a JSON API response into a Kubernetes manifest or CI config?

Yes — that is the canonical use case. API responses and generated config JSON convert to block YAML with structure preserved, so a JSON deployment spec becomes the indented manifest Kubernetes expects. For multi-document manifests, convert each JSON document separately and join the outputs with --- separators; the generator emits one document per conversion by design, so outputs compose without structural surprises.