JSON to TOON Converter — Token-Oriented Object Notation for LLM Prompts

Convert JSON to TOON locally in your browser. TOON is for LLM prompt input, not a replacement for JSON or YAML in APIs. Official spec: toonformat.dev. Pair with our token counter and pricing calculator. Round-trip with TOON → JSON.

…
Prompt-format conversion, not API storage
TOON compresses uniform tabular JSON for LLM prompts. FastMinify converts locally and shows honest token and USD deltas for your pasted payload.

How conversion works

We JSON.parse your input, then lazy-load @toon-format/toon v4.1.1 to encode TOON in the browser. Token counts reuse the same countTokensAsync path as the LLM token counter. USD estimates are input-only via estimateCostWithOptions — output tokens are zero.

Options that change TOON output

Row delimiter
Controls tabular row separators in TOON output. Tab often reduces tokens on large uniform tables; comma is more readable when debugging.
Indentation
Spaces per indent level when encoding. Matches the SDK default of 2 unless you need wider alignment.
Token model
Selects which tokenizer or heuristic drives the comparison panel and USD estimate. Does not change TOON bytes.

FAQ

TOON scope, savings, and privacy

Is TOON a replacement for JSON or YAML?

No. TOON targets LLM prompt input. Keep JSON/YAML for APIs, config files, and storage.

Why does TOON sometimes use more tokens?

Non-tabular or tiny objects add structure overhead. We show the real delta for your paste — including regressions.

Is my JSON uploaded?

No. Encoding and token counting run entirely in your browser.

Which TOON version do you ship?

We pin @toon-format/toon 4.1.1. See the official spec at toonformat.dev.

Are USD numbers billing-accurate?

They are estimates from our maintained price table (input tokens only). Verify on your provider invoice.

Should I minify JSON before converting?

The comparison uses your pasted string. Minified JSON may narrow TOON's advantage — measure both shapes if it matters.

AI & LLM

Token counting, pricing estimates, and context-window fit — 100% browser-local.

Explore other tool categories

Minify

Shrink code and assets for production — minify JavaScript, CSS, HTML, JSON and XML before gzip or CDN deploy.

Beautify

Make code readable with consistent indentation — beautify JavaScript, CSS, TypeScript, SCSS, LESS, Markdown, GraphQL, SQL, YAML and more in your browser.

Unminify

Expand minified or compressed code — unminify JavaScript, CSS, TypeScript, SCSS, LESS, SQL, YAML and other formats when debugging or reviewing.

Conversion

Transform data between JSON, YAML, XML and CSV locally — no server uploads.

CSS preprocessors

Compile SCSS or LESS to standard CSS in the browser — pair with beautify or minify for a full stylesheet workflow.

JSON Tools

Validate, format, diff and explore JSON payloads — complementary to minifiers and converters.

SVG Tools

Preview, optimize with SVGO, export Data URI, resize, beautify, convert to JSX and validate SVG — all in your browser.

DevOps & Infra

Terraform HCL format/validate/minify, Dockerfile format & lint, Docker Compose and .env validation.

CI/CD

GitHub Actions and GitLab CI — format YAML and check workflow/job structure in your browser.

Logs & observability

Line-oriented JSON/NDJSON and Nginx/Apache access logs — format, filter, validate, and CSV/TSV.

Kubernetes

Multi-doc manifests, structural validate, Ingress/Deployment starters, and Helm values formatting.

Networking / IP

CIDR, subnets, and IPv4/IPv6 helpers — in your browser.

Security & tokens

JWKS, X.509 certificates, and secrets scan — browser-local.

API & schemas

OpenAPI tools to format, validate, and lint your specs.

Encoding

Encode or decode Base64, URL components and HTML entities — client-side only.

Developer utilities

Timestamps, UUID, ULID, Nanoid, cron, passwords, regex, slugify, number bases, case, text diff, and chmod — all client-side.

Text & Markdown

Count words, build Markdown TOCs, and clean line lists — all in your browser.

Serialization

Serialize and deserialize PHP data structures beside JSON workflows.