Developer API Portal
Mass & Density REST API Documentation
Power your inventory software, recipe apps, fuel logistics platforms, construction tools, and AI agents with verified material conversion APIs.
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Test endpoints in real-time, generate client integration code, and access 700+ verified substance density records
REST v1.1API Online
Target Integrations & Real-World Use Cases
📦Inventory ERP
Bulk liquid stock balance
🍳Recipe Apps
Mass to volume scaling
⛽Fuel Logistics
Bunkering & fuel custody
🧪Chemistry Ed
Lab reagent solutions
🏗️Construction
Mix & aggregate sizing
🤖AI Agents
Scientific tool calling
GET/api/convert?mass=10&from=kg&to=liter&substance=diesel
Client Code Snippet
Response Inspector
200 OK12ms
HTTPStandard Endpoints Specification
| Method & Endpoint | Parameters / Body | Description |
|---|---|---|
| GET /api/convert | ?mass=10&from=kg&to=liter&substance=diesel | Converts mass to volume or volume to mass for any registered material. |
| GET /api/substances | ?page=1&limit=50&category=petroleum&search=diesel | Paginated catalogue query with search, category filtering, and min/max density. |
| GET /api/substances/:id | :id (e.g. water-pure, diesel-2) | Fetches complete substance metadata, reference temperature, and sources. |
| POST /api/convert/batch | { "substances": ["diesel", "water"], "massKg": 10 } | Bulk array conversion calculating volumes for multiple substances in one request. |
| GET /data/substances.json | None (Static JSON CDN) | Direct raw JSON download of all 700+ compiled density records. |
Developer FAQs
Frequently Asked Questions
Is an API key required to access the KgToLitre REST API or JSON catalogue?+
No API key is required. The static JSON catalogue (/data/substances.json) and query endpoints are open and CORS-enabled for web applications, mobile apps, and backend services.
How does the GET /api/convert endpoint work?+
You provide the mass, substance name or key, and units via query parameters (e.g. GET /api/convert?mass=10&from=kg&to=liter&substance=diesel). The API looks up the verified reference density and returns the exact converted volume, density, and applied formula.
Can I perform batch conversions in a single request?+
Yes. Use POST /api/convert/batch with a JSON payload of substance IDs (e.g. {"substances": ["diesel-2", "water-pure", "vegetable-oil"], "massKg": 10}) to convert multiple substances simultaneously.
Are results suitable for AI agents and LLM tool calling?+
Yes. The API returns standardized JSON with strict numerical types, making it ideal for function calling and deterministic unit conversions in AI agent pipelines.