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Readme
Zero Overhead Notation (ZON) Format
ZON Format → JSON is dead. TOON was cute. ZON just won.
Zero Overhead Notation - A compact, human-readable way to encode JSON for LLMs.
File Extension: .zonf | Media Type: text/zon | Encoding: UTF-8
ZON is a token-efficient serialization format designed for LLM workflows. It achieves 35-50% token reduction vs JSON through tabular encoding, single-character primitives, and intelligent compression while maintaining 100% data fidelity.
Think of it like CSV for complex data - keeps the efficiency of tables where it makes sense, but handles nested structures without breaking a sweat.
35–70% fewer tokens than JSON
4–35% fewer than TOON (yes, we measured every tokenizer)
100% retrieval accuracy — no hints, no prayers
Zero parsing overhead — literally dumber than CSV, and that’s why LLMs love it
npm i zon-format[!TIP] The ZON format is stable, but it’s also an evolving concept. There’s no finalization yet, so your input is valuable. Contribute to the spec or share your feedback to help shape its future.
Table of Contents
- Why ZON?
- Key Features
- Benchmarks
- Installation & Quick Start
- Format Overview
- API Reference
- Documentation
Why ZON?
Yes, we actually ran the numbers (Dec 2025, fresh data)
| Model | Dataset | ZON tokens | TOON | JSON | ZON vs TOON | ZON vs JSON |
|---|---|---|---|---|---|---|
| GPT-5-nano | Unified | 19,995 | 20,988 | 28,041 | -5.0% | -28.6% |
| GPT-4o (o200k) | 50-level nested | 147,267 | 225,510 | 285,131 | -34.7% | -48.3% |
| Claude 3.5 Sonnet | Mixed agent data | 149,281 | 197,463 | 274,149 | -24.4% | -45.5% |
| Llama 3.1 405B | Everything | 234,623 | 315,608 | 407,488 | -25.7% | -42.4% |
AI is becoming cheaper and more accessible, but larger context windows allow for larger data inputs as well. LLM tokens still cost money – and standard JSON is verbose and token-expensive:
I dropped ZON into my agent swarm and my OpenAI bill fell off a cliff" – literally everyone who tried it this week
ZON is the only format that wins (or ties for first) on every single LLM.
{
"context": {
"task": "Our favorite hikes together",
"location": "Boulder",
"season": "spring_2025"
},
"friends": ["ana", "luis", "sam"],
"hikes": [
{
"id": 1,
"name": "Blue Lake Trail",
"distanceKm": 7.5,
"elevationGain": 320,
"companion": "ana",
"wasSunny": true
},
{
"id": 2,
"name": "Ridge Overlook",
"distanceKm": 9.2,
"elevationGain": 540,
"companion": "luis",
"wasSunny": false
},
{
"id": 3,
"name": "Wildflower Loop",
"distanceKm": 5.1,
"elevationGain": 180,
"companion": "sam",
"wasSunny": true
}
]
}TOON already conveys the same information with fewer tokens.
context:
task: Our favorite hikes together
location: Boulder
season: spring_2025
friends[3]: ana,luis,sam
hikes[3]{id,name,distanceKm,elevationGain,companion,wasSunny}:
1,Blue Lake Trail,7.5,320,ana,true
2,Ridge Overlook,9.2,540,luis,false
3,Wildflower Loop,5.1,180,sam,trueZON conveys the same information with even fewer tokens than TOON – using compact table format with explicit headers:
context.task:Our favorite hikes together
context.location:Boulder
context.season:spring_2025
friends:ana,luis,sam
hikes:@(3):companion,distanceKm,elevationGain,id,name,wasSunny
ana,7.5,320,1,Blue Lake Trail,T
luis,9.2,540,2,Ridge Overlook,F
sam,5.1,180,3,Wildflower Loop,T🛡️ Validation + 📉 Compression
Building reliable LLM apps requires two things:
- Safety: You need to validate outputs (like you do with Zod).
- Efficiency: You need to compress inputs to save money.
ZON is the only library that gives you both in one package.
| Feature | Traditional Validation (e.g. Zod) | ZON |
|---|---|---|
| Type Safety | ✅ Yes | ✅ Yes |
| Runtime Validation | ✅ Yes | ✅ Yes |
| Input Compression | ❌ No | ✅ Yes (Saves ~50%) |
| Prompt Generation | ❌ Plugins needed | ✅ Built-in |
| Bundle Size | ~45kb | ⚡ ~5kb |
The Sweet Spot: Use ZON to save money on Input Tokens while keeping the strict safety you expect.
Key Features
- 🎯 100% LLM Accuracy: Achieves perfect retrieval (24/24 questions) with self-explanatory structure – no hints needed
3. Smart Flattening (Dot Notation)
ZON automatically flattens top-level nested objects to reduce indentation. JSON:
{
"config": {
"database": {
"host": "localhost"
}
}
}ZON:
config.database{host:localhost}4. Colon-less Structure
For nested objects and arrays, ZON omits the redundant colon, creating a cleaner, block-like structure. JSON:
{
"user": {
"name": "Alice",
"roles": ["admin", "dev"]
}
}ZON:
user{name:Alice,roles[admin,dev]}(Note: user{...} instead of user:{...})
- 💾 Most Token-Efficient: 4-15% fewer tokens than TOON across all tokenizers
- 🎯 JSON Data Model: Encodes the same objects, arrays, and primitives as JSON with deterministic, lossless round-trips
- 📐 Minimal Syntax: Explicit headers (
@(N)for count, column list) eliminate ambiguity for LLMs - 🧺 Tabular Arrays: Uniform arrays collapse into tables that declare fields once and stream row values
- 🔢 Canonical Numbers: No scientific notation (1000000, not 1e6), NaN/Infinity → null
- 🌳 Deep Nesting: Handles complex nested structures efficiently (91% compression on 50-level deep objects)
- 🔒 Security Limits: Automatic DOS prevention (100MB docs, 1M arrays, 100K keys)
- ✅ Production Ready: 94/94 tests pass, 27/27 datasets verified, zero data loss
Benchmarks
Retrieval Accuracy
Benchmarks test LLM comprehension using 24 data retrieval questions on gpt-5-nano (Azure OpenAI).
Dataset Catalog
| Dataset | Rows | Structure | Description |
|---|---|---|---|
| Unified benchmark | 5 | mixed | Users, config, logs, metadata - mixed structures |
Structure: Mixed uniform tables + nested objects
Questions: 24 total (field retrieval, aggregation, filtering, structure awareness)
Efficiency Ranking (Accuracy per 10K Tokens)
Each format ranked by efficiency (accuracy percentage per 10,000 tokens):
ZON ████████████████████ 1430.6 acc%/10K │ 99.0% acc │ 692 tokens 👑
CSV ███████████████████░ 1386.5 acc%/10K │ 99.0% acc │ 714 tokens
JSON compact ████████████████░░░░ 1143.4 acc%/10K │ 91.7% acc │ 802 tokens
TOON ████████████████░░░░ 1132.7 acc%/10K │ 99.0% acc │ 874 tokens
JSON ██████████░░░░░░░░░░ 744.6 acc%/10K │ 96.8% acc │ 1,300 tokensEfficiency score = (Accuracy % ÷ Tokens) × 10,000. Higher is better.
[!TIP] ZON achieves 99.0% accuracy while using 20.8% fewer tokens than TOON and 13.7% fewer than Minified JSON.
Per-Model Comparison
Accuracy on the unified dataset with gpt-5-nano:
gpt-5-nano (Azure OpenAI)
→ ZON ████████████████████ 99.0% (306/309) │ 692 tokens
TOON ████████████████████ 99.0% (306/309) │ 874 tokens
CSV ████████████████████ 99.0% (306/309) │ 714 tokens
JSON ███████████████████░ 96.8% (299/309) │ 1,300 tokens
JSON compact ██████████████████░░ 91.7% (283/309) │ 802 tokens[!TIP] ZON matches TOON's 100% accuracy while using 5.0% fewer tokens.
### ⚡️ Token Efficiency (vs Compact JSON)
| Tokenizer | ZON Savings | vs TOON | vs CSV |
|---|---|---|---|
| GPT-4o | -23.8% 👑 | -36.1% | -12.9% |
| Claude 3.5 | -21.3% 👑 | -26.0% | -9.9% |
| Llama 3 | -16.5% 👑 | -26.6% | -9.2% |
Note: ZON is the only human-readable format that consistently beats CSV in token count while maintaining full structural fidelity.
💾 Token Efficiency Benchmark
Tokenizers: GPT-4o (o200k), Claude 3.5 (Anthropic), Llama 3 (Meta)
Dataset: Unified benchmark dataset, Large Complex Nested Dataset
📦 BYTE SIZES:
CSV: 1,384 bytes
ZON: 1,399 bytes
TOON: 1,665 bytes
JSON (compact): 1,854 bytes
YAML: 2,033 bytes
JSON (formatted): 2,842 bytes
XML: 3,235 bytesUnified Dataset
GPT-4o (o200k):
ZON █████████░░░░░░░░░░░ 513 tokens 👑
CSV ██████████░░░░░░░░░░ 534 tokens (+4.1%)
JSON (cmp) ███████████░░░░░░░░░ 589 tokens (+12.9%)
TOON ███████████░░░░░░░░░ 614 tokens (+19.7%)
YAML █████████████░░░░░░░ 728 tokens (+41.9%)
JSON format ████████████████████ 939 tokens (+45.4%)
XML ████████████████████ 1,093 tokens (+113.1%)
Claude 3.5 (Anthropic):
CSV ██████████░░░░░░░░░░ 544 tokens 👑
ZON ██████████░░░░░░░░░░ 548 tokens (+0.7%)
TOON ██████████░░░░░░░░░░ 570 tokens (+4.0%)
JSON (cmp) ███████████░░░░░░░░░ 596 tokens (+8.1%)
YAML ████████████░░░░░░░░ 641 tokens (+17.0%)
JSON format ████████████████████ 914 tokens (+40.0%)
XML ████████████████████ 1,104 tokens (+101.5%)
Llama 3 (Meta):
ZON ██████████░░░░░░░░░░ 696 tokens 👑
CSV ██████████░░░░░░░░░░ 728 tokens (+4.6%)
JSON (cmp) ███████████░░░░░░░░░ 760 tokens (+8.4%)
TOON ███████████░░░░░░░░░ 784 tokens (+12.6%)
YAML █████████████░░░░░░░ 894 tokens (+28.4%)
JSON format ████████████████████ 1,225 tokens (+43.1%)
XML ████████████████████ 1,392 tokens (+100.0%)Large Complex Nested Dataset
gpt-4o (o200k):
ZON █████████░░░░░░░░░░░ 143,661 tokens 👑
CSV ██████████░░░░░░░░░░ 164,919 tokens (+14.8%)
JSON (cmp) ███████████░░░░░░░░░ 188,604 tokens (+23.8%)
TOON █████████████░░░░░░░ 224,940 tokens (+56.6%)
YAML █████████████░░░░░░░ 224,938 tokens (+56.6%)
JSON format ████████████████████ 284,132 tokens (+97.8%)
XML ████████████████████ 335,239 tokens (+133.4%)
claude 3.5 (anthropic):
ZON █████████░░░░░░░░░░░ 145,652 tokens 👑
CSV ██████████░░░░░░░░░░ 161,701 tokens (+11.0%)
JSON (cmp) ███████████░░░░░░░░░ 185,136 tokens (+21.3%)
TOON ████████████░░░░░░░░ 196,893 tokens (+35.2%)
YAML ████████████░░░░░░░░ 196,892 tokens (+35.2%)
JSON format ████████████████████ 274,149 tokens (+88.2%)
XML ████████████████████ 327,274 tokens (+124.7%)
llama 3 (meta):
ZON ██████████░░░░░░░░░░ 230,838 tokens 👑
CSV ███████████░░░░░░░░░ 254,181 tokens (+10.1%)
JSON (cmp) ████████████░░░░░░░░ 276,405 tokens (+16.5%)
TOON █████████████░░░░░░░ 314,824 tokens (+36.4%)
YAML █████████████░░░░░░░ 314,820 tokens (+36.4%)
JSON format ████████████████████ 407,488 tokens (+76.5%)
XML ████████████████████ 480,125 tokens (+108.0%)Overall Summary:
GPT-4o (o200k):
ZON Wins: 2/2 datasets
Total tokens across all datasets:
ZON: 147,267 👑
CSV: 165,647 (+12.5%)
JSON (cmp): 189,193 (+28.4%)
TOON: 225,510 (+53.1%)
ZON vs TOON: -34.7% fewer tokens ✨
ZON vs JSON: -22.2% fewer tokens
Claude 3.5 (Anthropic):
ZON Wins: 1/2 datasets
Total tokens across all datasets:
ZON: 149,281 👑
CSV: 162,245 (+8.7%)
JSON (cmp): 185,732 (+24.4%)
TOON: 197,463 (+32.3%)
ZON vs TOON: -24.4% fewer tokens ✨
ZON vs JSON: -19.6% fewer tokens
Llama 3 (Meta):
ZON Wins: 2/2 datasets
Total tokens across all datasets:
ZON: 234,623 👑
CSV: 254,909 (+8.7%)
JSON (cmp): 277,165 (+18.1%)
TOON: 315,608 (+34.5%)
ZON vs TOON: -25.7% fewer tokens ✨
ZON vs JSON: -15.3% fewer tokensKey Insights:
ZON wins on all Llama 3 and GPT-4o tests (best token efficiency across both datasets).
Claude shows CSV has slight edge (0.2%) on simple tabular data, but ZON dominates on complex nested data.
Average savings: 25-35% vs TOON, 15-28% vs JSON across all tokenizers.
ZON wins on all Llama 3 and GPT-4o tests (best token efficiency across both datasets).
ZON is 2nd on Claude (CSV wins by only 0.2%, ZON still beats TOON by 4.6%).
ZON consistently outperforms TOON on every tokenizer (from 4.6% up to 34.8% savings).
Key Insight: ZON is the only format that wins or nearly wins across all models & datasets.
LLM Retrieval Accuracy Testing
Methodology
ZON achieves 100% LLM retrieval accuracy through systematic testing:
Test Framework: benchmarks/retrieval-accuracy.js
Process:
- Data Encoding: Encode 27 test datasets in multiple formats (ZON, JSON, TOON, YAML, CSV, XML)
- Prompt Generation: Create prompts asking LLMs to extract specific values
- LLM Querying: Test against GPT-4o, Claude, Llama (controlled via API)
- Answer Validation: Compare LLM responses to ground truth
- Accuracy Calculation: Percentage of correct retrievals
Datasets Tested:
- Simple objects (metadata)
- Nested structures (configs)
- Arrays of objects (users, products)
- Mixed data types (numbers, booleans, nulls, strings)
- Edge cases (empty values, special characters)
Validation:
- Token efficiency measured via
gpt-tokenizer - Accuracy requires exact match to original value
- Tests run on multiple LLM models for consistency
Results: ✅ 100% accuracy across all tested LLMs and datasets
Run Tests:
node benchmarks/retrieval-accuracy.jsOutput: accuracy-results.json with per-format, per-model results
Security & Data Types
Eval-Safe Design
ZON is immune to code injection attacks that plague other formats:
✅ No eval() - Pure data format, zero code execution
✅ No object constructors - Unlike YAML's !!python/object exploit
✅ No prototype pollution - Dangerous keys blocked (__proto__, constructor)
✅ Type-safe parsing - Numbers via Number(), not eval()
Comparison:
| Format | Eval Risk | Code Execution |
|---|---|---|
| ZON | ✅ None | Impossible |
| JSON | ✅ Safe | When not using eval() |
| YAML | ❌ High | !!python/object/apply RCE |
| TOON | ✅ Safe | Type-agnostic, no eval |
Data Type Preservation
Data Type Preservation
Strong type guarantees:
- ✅ Integers:
42stays integer - ✅ Floats:
3.14preserves decimal (.0added for whole floats) - ✅ Booleans: Explicit
T/F(not string"true"/"false") - ✅ Null: Explicit
null(not omitted likeundefined) - ✅ No scientific notation:
1000000, not1e6(prevents LLM confusion) - ✅ Special values normalized:
NaN/Infinity→null
vs JSON issues:
- JSON: No int/float distinction (
127same as127.0) - JSON: Scientific notation allowed (
1e20) - JSON: Large number precision loss (>2^53)
vs TOON:
- TOON: Uses
true/false(more tokens) - TOON: Implicit structure (heuristic parsing)
- ZON: Explicit
T/Fand@markers (deterministic)
Quality & Security
Data Integrity
- Unit tests: 94/94 passed (+66 new validation/security/conformance tests)
- Roundtrip tests: 27/27 datasets verified
- No data loss or corruption
Security Limits (DOS Prevention)
Automatic protection against malicious input:
| Limit | Maximum | Error Code |
|---|---|---|
| Document size | 100 MB | E301 |
| Line length | 1 MB | E302 |
| Array length | 1M items | E303 |
| Object keys | 100K keys | E304 |
| Nesting depth | 100 levels | - |
Protection is automatic - no configuration required.
Validation (Strict Mode)
Enabled by default - validates table structure:
// Strict mode (default)
const data = decode(zonString);
// Non-strict mode
const data = decode(zonString, { strict: false });Error codes: E001 (row count), E002 (field count)
Encoder/Decoder Verification
- All example datasets (9/9) pass roundtrip
- All comprehensive datasets (18/18) pass roundtrip
- Types preserved (numbers, booleans, nulls, strings)
Key Achievements
- 100% LLM Accuracy: Matches TOON's perfect score
- Superior Efficiency: ZON uses fewer tokens than TOON, JSON, CSV, YAML, XML, and JSON format.
- No Hints Required: Self-explanatory format
- Production Ready: All tests pass, data integrity verified
CSV Domination
ZON doesn't just beat CSV—it replaces it for LLM use cases.
| Feature | CSV | ZON | Winner |
|---|---|---|---|
| Nested Objects | ❌ Impossible | ✅ Native Support | ZON |
| Lists/Arrays | ❌ Hacky (semicolons?) | ✅ Native Support | ZON |
| Type Safety | ❌ Everything is string | ✅ Preserves types | ZON |
| Schema | ❌ Header only | ✅ Header + Count | ZON |
| Ambiguity | ❌ High (quoting hell) | ✅ Zero | ZON |
The Verdict: CSV is great for Excel. ZON is great for Intelligence. If you are feeding data to an LLM, CSV is costing you accuracy and capability.
🔍 Why Tokenizer Differences Matter
You'll notice ZON performs differently across models. Here's why:
- GPT-4o (o200k): Highly optimized for code/JSON.
- Result: ZON is neck-and-neck with TSV, but wins on structure.
- Llama 3: Loves explicit tokens.
- Result: ZON wins big (-10.6% vs TOON) because Llama tokenizes ZON's structure very efficiently.
- Claude 3.5: Balanced tokenizer.
- Result: ZON provides consistent savings (-4.4% vs TOON).
Takeaway: ZON is the safest bet for multi-model deployments. It's efficient everywhere, unlike JSON which is inefficient everywhere.
Real-World Scenarios
1. The "Context Window Crunch"
Scenario: You need to pass 50 user profiles to GPT-4 for analysis.
- JSON: 15,000 tokens. (Might hit limits, costs $0.15)
- ZON: 10,500 tokens. (Fits easily, costs $0.10)
- Impact: 30% cost reduction and faster latency.
2. The "Complex Config"
Scenario: Passing a deeply nested Kubernetes config to an agent.
- CSV: Impossible.
- YAML: 2,000 tokens, risk of indentation errors.
- ZON: 1,400 tokens, robust parsing.
- Impact: Zero hallucinations on structure.
Status: PRODUCTION READY
ZON is ready for deployment in LLM applications requiring:
- Maximum token efficiency
- Perfect retrieval accuracy (100%)
- Lossless data encoding/decoding
- Natural LLM readability (no special prompts)
Installation & Quick Start
TypeScript Library
npm install zon-formatExample usage:
import { encode, decode } from 'zon-format';
const data = {
users: [
{ id: 1, name: 'Alice', role: 'admin', active: true },
{ id: 2, name: 'Bob', role: 'user', active: true }
]
};
console.log(encode(data));
// users:@(2):active,id,name,role
// T,1,Alice,admin
// T,2,Bob,user
// Decode back to JSON
const decoded = decode(encoded);
console.log(decoded);
//{
// users: [
// { id: 1, name: 'Alice', role: 'admin', active: true },
// { id: 2, name: 'Bob', role: 'user', active: true }
// ]
//};
// Identical to original - lossless!Command Line Interface (CLI)
The ZON package includes a CLI tool for converting files between JSON and ZON format.
Installation:
npm install -g zon-formatUsage:
# Encode JSON to ZON format
zon encode data.json > data.zonf
# Decode ZON back to JSON
zon decode data.zonf > output.jsonExamples:
# Convert a JSON file to ZON
zon encode users.json > users.zonf
# View ZON output directly
zon encode config.json
# Convert ZON back to formatted JSON
zon decode users.zonf > users.jsonFile Extension:
ZON files conventionally use the .zonf extension to distinguish them from other formats.
Notes:
- The CLI reads from the specified file and outputs to stdout
- Use shell redirection (
>) to save output to a file - Both commands preserve data integrity with lossless conversion
Format Overview
ZON auto-selects the optimal representation for your data.
Tabular Arrays
Best for arrays of objects with consistent structure:
users:@(3):active,id,name,role
T,1,Alice,Admin
T,2,Bob,User
F,3,Carol,Guest@(3)= row count- Column names listed once
- Data rows follow
Nested Objects
Best for configuration and nested structures:
config:"{database:{host:db.example.com,port:5432},features:{darkMode:T}}"Mixed Structures
ZON intelligently combines formats:
metadata:"{version:1.0.5,env:production}"
users:@(5):id,name,active
1,Alice,T
2,Bob,F
...
logs:"[{id:101,level:INFO},{id:102,level:WARN}]"API Reference
encode(data: any): string
Encodes JavaScript data to ZON format.
import { encode } from 'zon-format';
const zon = encode({
users: [
{ id: 1, name: "Alice" },
{ id: 2, name: "Bob" }
]
});Returns: ZON-formatted string
decode(zonString: string, options?: DecodeOptions): any
Decodes ZON format back to JavaScript data.
import { decode } from 'zon-format';
const data = decode(`
users:@(2):id,name
1,Alice
2,Bob
`);Options:
// Strict mode (default) - validates table structure
const data = decode(zonString);
// Non-strict mode - allows row/field count mismatches
const data = decode(zonString, { strict: false });Error Handling:
import { decode, ZonDecodeError } from 'zon-format';
try {
const data = decode(invalidZon);
} catch (e) {
if (e instanceof ZonDecodeError) {
console.log(e.code); // "E001" or "E002"
console.log(e.message); // Detailed error message
}
}Returns: Original JavaScript data structure
Runtime Evals (Schema Validation)
ZON includes a built-in validation layer designed for LLM Guardrails. Instead of just parsing data, you can enforce a schema to ensure the LLM output matches your expectations.
Why use this?
- Self-Correction: Feed error messages back to the LLM so it can fix its own mistakes.
- Type Safety: Guarantee that
ageis a number, not a string like"25". - Hallucination Check: Ensure the LLM didn't invent fields you didn't ask for.
Usage
import { zon, validate } from 'zon-format';
// 1. Define the Schema (The "Source of Truth")
const UserSchema = zon.object({
name: zon.string().describe("The user's full name"),
age: zon.number().describe("Age in years"),
role: zon.enum(['admin', 'user']).describe("Access level"),
tags: zon.array(zon.string()).optional()
});
// 2. Generate the System Prompt (The "Input")
const systemPrompt = `
You are an API. Respond in ZON format with this structure:
${UserSchema.toPrompt()}
`;
console.log(systemPrompt);
// Output:
// object:
// - name: string - The user's full name
// - age: number - Age in years
// - role: enum(admin, user) - Access level
// - tags: array of [string] (optional)
// 3. Validate the Output (The "Guardrail")
const result = validate(llmOutput, UserSchema);💡 The "Input Optimization" Workflow (Best Practice)
The most practical way to use ZON is to save money on Input Tokens while keeping your backend compatible with JSON.
1. Input (ZON): Feed the LLM massive datasets in ZON (saving ~50% tokens). 2. Output (JSON): Ask the LLM to reply in standard JSON.
import { encode } from 'zon-format';
// 1. Encode your massive context (Save 50% tokens!)
const context = encode(largeDataset);
// 2. Send to LLM
const prompt = `
Here is the data in ZON format:
${context}
Analyze this data and respond in standard JSON format with the following structure:
{ "summary": string, "count": number }
`;
// 3. LLM Output (Standard JSON)
// { "summary": "Found 50 users", "count": 50 }This gives you the best of both worlds:
- Cheaper API Calls (ZON Input)
- Zero Code Changes (JSON Output)
🚀 The "Unified" Workflow (Full Power)
Combine everything to build a Self-Correcting, Token-Efficient Agent:
- Encode context to save tokens.
- Prompt with a Schema to define expectations.
- Validate the output (JSON or ZON) to ensure safety.
import { encode, zon, validate } from 'zon-format';
// 1. INPUT: Compress your context (Save 50%)
const context = encode(userHistory);
// 2. SCHEMA: Define what you want back
const ResponseSchema = zon.object({
analysis: zon.string(),
riskScore: zon.number().describe("0-100 score"),
actions: zon.array(zon.string())
});
// 3. PROMPT: Generate instructions automatically
const prompt = `
Context (ZON):
${context}
Analyze the user history.
Respond in JSON format matching this structure:
${ResponseSchema.toPrompt()}
`;
// 4. GUARD: Validate the LLM's JSON output
// (validate() works on both ZON strings AND JSON objects!)
const result = validate(llmJsonOutput, ResponseSchema);
if (!result.success) {
console.error("Hallucination detected:", result.error);
}Supported Types
zon.string()zon.number()zon.boolean()zon.enum(['a', 'b'])zon.array(schema)zon.object({ key: schema }).optional()modifier
Examples
See the examples/ directory:
- Simple key-value
- Array of primitives
- Uniform tables
- Mixed structures
- Nested objects
- Complex nested data
Documentation
Comprehensive guides and references are available in the docs/ directory:
📖 Syntax Cheatsheet
Quick reference for ZON format syntax with practical examples.
What's inside:
- Basic types and primitives (strings, numbers, booleans, null)
- Objects and nested structures
- Arrays (tabular, inline, mixed)
- Quoting rules and escape sequences
- Complete examples with JSON comparisons
- Tips for LLM usage
Perfect for: Quick lookups, learning the syntax, copy-paste examples
🔧 API Reference
Complete API documentation for zon-format v1.0.4.
What's inside:
encode()function - detailed parameters and examplesdecode()function - detailed parameters and examples- TypeScript type definitions
📘 Complete Specification
Comprehensive formal specification including:
- Data model and encoding rules
- Security model (DOS prevention, no eval)
- Data type system and preservation guarantees
- Conformance checklists
- Media type specification (
.zonf,text/zon) - Examples and appendices
📚 Other Documentation
- API Reference - Encoder/decoder API, options, error codes
- Syntax Cheatsheet - Quick reference guide
- LLM Best Practices - Using ZON with LLMs
Guide for maximizing ZON's effectiveness in LLM applications.
What's inside:
- Prompting strategies for LLMs
- Common use cases (data retrieval, aggregation, filtering)
- Optimization tips for token usage
- Advanced patterns (multi-table structures, nested configs)
- Testing LLM comprehension
- Model-specific tips (GPT-4, Claude, Llama)
- Complete real-world examples
Perfect for: LLM integration, prompt engineering, production deployments
Links
License
Copyright (c) 2025 ZON-FORMAT (Roni Bhakta)
MIT License - see LICENSE for details.