LAPIS

aid: lapis
name: LAPIS
description: LAPIS (Lightweight API Specification for Intelligent Systems) is a compact, LLM-native API description format
  authored by Daniel Garcia (cr0hn). It is designed as the format you convert your OpenAPI specifications to when the consumer
  is a Large Language Model rather than a code generator or human reader. By replacing JSON/YAML structural overhead with
  a function-signature syntax, indentation-based sections, and centralized definitions for errors, webhooks, rate limits,
  and workflows, a typical LAPIS document carries the same semantic information as its OpenAPI source while consuming roughly
  70-80 percent fewer tokens. LAPIS is not a runtime format and does not replace MCP, function calling, or OpenAPI itself
  - it is an intermediate representation optimized for AI agents that need to reason about an API inside a constrained context
  window.
type: Index
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
tags:
- API
- Specification
- LLM
- AI Agents
- OpenAPI
- Token Optimization
- Standards
url: https://raw.githubusercontent.com/api-evangelist/lapis/refs/heads/main/apis.yml
created: '2026-05-06'
modified: '2026-05-06'
specificationVersion: '0.19'
apis:
- aid: lapis:lapis-spec
  name: LAPIS Specification
  description: The LAPIS specification defines a token-minimal, LLM-native format for describing HTTP APIs. A LAPIS document
    is organized into up to seven indentation-based sections - [meta], [types], [ops], [webhooks], [errors], [limits], and
    [flows] - each carrying a focused slice of the API contract. The format draws its syntax from function signatures rather
    than nested data structures, uses scalar types (str, int, float, bool, date, datetime, file, any) with array, map, optional,
    and default modifiers, and centralizes cross-cutting concerns like errors and rate limits so they are described once and
    applied globally. The current release is version 0.1.0 (status Draft) released 2026-02-16 under the Creative Commons Attribution
    4.0 license, and the specification is published in both English and Spanish.
  humanURL: https://github.com/cr0hn/LAPIS/blob/main/spec.en.md
  tags:
  - Specification
  - LLM
  - OpenAPI
  - Standards
  properties:
  - type: Documentation
    url: https://github.com/cr0hn/LAPIS/blob/main/spec.en.md
    title: LAPIS Specification (English)
  - type: Documentation
    url: https://github.com/cr0hn/LAPIS/blob/main/spec.es.md
    title: LAPIS Specification (Spanish)
  - type: APIReference
    url: https://github.com/cr0hn/LAPIS/blob/main/spec.en.md#16-formal-grammar-simplified-ebnf
    title: Formal EBNF Grammar
  - type: ChangeLog
    url: https://github.com/cr0hn/LAPIS/blob/main/CHANGELOG.md
    title: Changelog
  - type: GettingStarted
    url: https://github.com/cr0hn/LAPIS/blob/main/spec-example.en.md
    title: Walk-Through Example (English)
  - type: GettingStarted
    url: https://github.com/cr0hn/LAPIS/blob/main/spec-example.es.md
    title: Walk-Through Example (Spanish)
  - type: GitHubRepository
    url: https://github.com/cr0hn/LAPIS
    title: Canonical Specification Repository
  - type: Versioning
    url: https://github.com/cr0hn/LAPIS/releases
    title: Releases
  - type: Examples
    url: https://github.com/cr0hn/LAPIS/blob/main/examples/DigitalOcean-public.v2.lapis
    title: DigitalOcean Public API v2 (LAPIS)
  - type: Examples
    url: https://github.com/cr0hn/LAPIS/blob/main/examples/DigitalOcean-public.v2.yaml
    title: DigitalOcean Public API v2 (OpenAPI Source)
common:
- type: Portal
  url: https://cr0hn.github.io/LAPIS/
  title: LAPIS Online Converter
- type: Documentation
  url: https://github.com/cr0hn/LAPIS/blob/main/spec.en.md
  title: Specification (English)
- type: Documentation
  url: https://github.com/cr0hn/LAPIS/blob/main/spec.es.md
  title: Specification (Spanish)
- type: GettingStarted
  url: https://github.com/cr0hn/LAPIS#getting-started
  title: Getting Started
- type: GitHubRepository
  url: https://github.com/cr0hn/LAPIS
  title: LAPIS Repository
- type: ChangeLog
  url: https://github.com/cr0hn/LAPIS/blob/main/CHANGELOG.md
  title: Changelog
- type: TermsOfService
  url: https://github.com/cr0hn/LAPIS/blob/main/LICENSE
  title: License (CC BY 4.0)
- type: Compliance
  url: https://github.com/cr0hn/LAPIS/blob/main/CODE_OF_CONDUCT.md
  title: Code of Conduct
- type: Security
  url: https://github.com/cr0hn/LAPIS/blob/main/SECURITY.md
  title: Security Policy
- type: Contact
  url: https://github.com/cr0hn/LAPIS/blob/main/CONTRIBUTING.md
  title: Contributing Guide
- type: CLI
  url: https://pypi.org/project/lapis-spec/
  title: lapis CLI (lapis-spec on PyPI)
- type: SDKs
  url: https://pypi.org/project/lapis-spec/
  title: lapis-spec Python Package
- type: IDESupport
  url: https://github.com/cr0hn/LAPIS/tree/main/tools/ides/vscode
  title: LAPIS Visual Studio Code Extension
- type: Sandbox
  url: https://cr0hn.github.io/LAPIS/
  title: Browser-Based OpenAPI to LAPIS Converter
- type: Issues
  url: https://github.com/cr0hn/LAPIS/issues
  title: Issue Tracker
- type: Vocabulary
  url: vocabulary/lapis-vocabulary.yml
  title: LAPIS Normative Vocabulary
- type: JSONSchema
  url: json-schema/lapis-document-schema.json
  title: LAPIS Document JSON Schema
- type: JSONStructure
  url: json-structure/lapis-document-structure.json
  title: LAPIS Document JSON Structure
- type: JSONLD
  url: json-ld/lapis-context.jsonld
  title: LAPIS JSON-LD Context
- type: Examples
  url: examples/lapis-invoice-service-example.lapis
  title: Invoice Service LAPIS Example
- type: Examples
  url: examples/lapis-meta-section-example.lapis
  title: Meta Section Example
- type: Examples
  url: examples/lapis-types-section-example.lapis
  title: Types Section Example
- type: Examples
  url: examples/lapis-ops-section-example.lapis
  title: Operations Section Example
- type: Examples
  url: examples/lapis-webhooks-section-example.lapis
  title: Webhooks Section Example
- type: Examples
  url: examples/lapis-errors-section-example.lapis
  title: Errors Section Example
- type: Examples
  url: examples/lapis-limits-section-example.lapis
  title: Limits Section Example
- type: Examples
  url: examples/lapis-flows-section-example.lapis
  title: Flows Section Example
- type: Features
  data:
  - name: Function-Signature Syntax for APIs
    description: LAPIS uses operation headers shaped like function signatures (operation_name METHOD /path), input parameters
      prefixed with > and outputs prefixed with <, so an LLM reads each endpoint as a callable rather than as a deeply nested
      JSON object.
  - name: Seven-Section Document Model
    description: A LAPIS document is composed of up to seven sections in a fixed order - [meta], [types], [ops], [webhooks],
      [errors], [limits], and [flows] - with [meta] and [ops] required and the remainder optional based on what the API actually
      exposes.
  - name: Centralized Error Definitions
    description: Errors are declared once in [errors] using HTTP code plus a snake_case identifier, optionally bound to specific
      operations via @ops:name1,name2, eliminating the per-operation duplication of 400/401/404/429 responses that bloats
      OpenAPI documents.
  - name: First-Class Webhook Triggers
    description: The [webhooks] section captures both the payload shape and the trigger condition (lines prefixed with !)
      that fires the event, giving an LLM the why of an event rather than only the what that OpenAPI delivers.
  - name: Structured Rate Limits and Quotas
    description: The [limits] section expresses rate limits, quotas, body size caps, batch size caps, and tiered plan blocks
      as first-class declarative fields with scope annotations like @key, @global, @ip, @user, and @op:operation_name.
  - name: Multi-Step Workflow Flows
    description: The [flows] section describes how operations chain together using step1 -> step2 -> step3 notation, with
      branches (|), loops (*), waits (...(condition)), and inter-step data passing (op.field -> next_op(field)) so an agent
      learns canonical usage patterns alongside individual endpoints.
  - name: Field Versioning and Deprecation
    description: Field-level @since:X.Y annotations let an LLM determine whether a given field exists at the API version declared
      in [meta], and @deprecated optionally followed by a quoted note marks fields and operations that should not be used
      by new integrations.
  - name: Operation Modifiers
    description: Operations can carry +paginated, +deprecated, +idempotent, and +stream modifiers appended after the path,
      signaling pagination, retry safety, streaming response semantics, and deprecation status without verbose extension blocks.
  - name: Inline Object Types
    description: 'Types used by only a single operation can be inlined directly in the parameter list using {field: type,
      field: type} or [{field: type}] notation, avoiding pollution of [types] with single-use schemas.'
  - name: 70-80 Percent Token Reduction
    description: For a representative mid-size API (11 operations, 8 types, 3 webhooks, 10 errors, limits, 4 flows), LAPIS
      measures roughly 1,500 tokens versus 6,500 for the equivalent OpenAPI YAML, a 0.23x ratio driven primarily by removing
      irrelevant metadata, repeated error definitions, and JSON/YAML key restatement.
  - name: Deterministic OpenAPI Conversion
    description: Section 14 of the spec defines field-by-field rules for converting OpenAPI 3.x into LAPIS, covering info,
      servers, securitySchemes, components.schemas, paths, webhooks, x-rateLimit and x-quota extensions, and links, making
      the conversion fully automatable.
  - name: Formal EBNF Grammar
    description: The specification ships a simplified EBNF grammar covering all seven sections, type expressions, modifiers,
      annotations, comments, and primitive lexical tokens, providing a normative reference for tool authors building parsers,
      linters, and highlighters.
  - name: Bilingual Specification
    description: The LAPIS specification is published in parallel English (spec.en.md) and Spanish (spec.es.md) editions,
      with matching walk-through examples (spec-example.en.md and spec-example.es.md) that narrate a sample Invoice Service
      API in both languages.
- type: UseCases
  data:
  - name: Reducing LLM Context Cost
    description: Engineering teams whose AI features pass an OpenAPI specification into prompts on every call convert the
      spec to LAPIS once and pass the smaller LAPIS document instead, reducing per-call token spend by roughly 70-80 percent
      on the API description portion of the context window.
  - name: Powering AI Coding Assistants
    description: AI coding assistants that need to reason about a third-party API (generating client code, debugging a failing
      call, suggesting an endpoint) consume LAPIS as the API context layer, freeing more of the context window for the actual
      user prompt and conversation history.
  - name: Multi-Step API Agent Planning
    description: AI agents executing multi-step API workflows (create customer, create invoice, send invoice, await payment
      webhook) load a LAPIS document with a populated [flows] section so the planner has canonical workflow templates rather
      than having to infer chaining from individual operation descriptions.
  - name: Webhook-Aware Integrations
    description: Integration platforms that build webhook receivers use the [webhooks] section's trigger conditions (!) and
      headers (@header:X-Event-ID) to generate signature verification and event dispatch logic that knows when each event
      should fire and what identifying headers to expect.
  - name: Plan-Aware Rate Limit Enforcement
    description: Client SDKs and gateway integrations consume the [limits] section to configure backoff, request-throttling,
      and quota tracking per plan tier (free, pro, enterprise) and per scope (@key, @user, @op:name) without reading provider
      documentation in prose.
  - name: Specification Linting and Validation
    description: Tooling vendors and platform teams enforce LAPIS-conformant documents by validating against the EBNF grammar
      in spec section 16, catching missing required sections, invalid type expressions, and malformed annotations before the
      document is shipped to downstream consumers.
  - name: Cross-Provider API Comparison
    description: Because LAPIS strips presentation overhead and centralizes errors, limits, and flows, two LAPIS documents
      from different providers can be diffed and compared more directly than two OpenAPI specifications.
  - name: Onboarding Documentation for Internal APIs
    description: Platform teams generate LAPIS from internal OpenAPI sources to provide on-call engineers and product stakeholders
      a quickly readable, function-signature view of the company's services alongside the long-form OpenAPI documentation.
- type: Integrations
  data:
  - name: OpenAPI 3.0 and 3.1
    description: OpenAPI is the canonical source format for LAPIS. The lapis-spec Python tool ingests OpenAPI 3.0.x and 3.1.x
      in JSON or YAML, resolves $ref including circular references, flattens allOf/oneOf/anyOf, deduplicates inline versus
      named types, and emits a LAPIS document.
  - name: PyPI (lapis-spec)
    description: The reference command-line converter is published to PyPI as lapis-spec and exposes a lapis console script.
      Installation is pip install lapis-spec or uv pip install lapis-spec, and the CLI accepts -i/--input, -o/--output, and
      --no-validate flags.
  - name: Visual Studio Code
    description: The LAPIS Language extension (publisher lapis-spec, identifier lapis-lang) provides syntax highlighting for
      .lapis files, including section headers, scalar types, modifiers, IO markers, annotations, bracket matching, auto-closing
      pairs, and section folding.
  - name: Web Browser Converter
    description: A static JavaScript single-page application at https://cr0hn.github.io/LAPIS/ runs the OpenAPI to LAPIS conversion
      entirely in the browser via converter.js, highlighter.js, and app.js, supporting drag-and-drop, paste, copy, and download
      of .lapis files.
  - name: MCP and Function Calling
    description: LAPIS is positioned alongside (not as a replacement for) MCP and function calling. A LAPIS document is the
      context-layer description an LLM reads to understand an API; MCP servers and function-calling schemas remain the runtime
      invocation layer for actually executing operations.
  - name: Creative Commons Attribution 4.0
    description: The specification text is licensed under CC BY 4.0, allowing adaptation, distribution, and commercial use
      provided attribution is given. The reference tooling (lapis-spec Python package) is MIT licensed, and the VS Code extension
      is CC BY 4.0.
  - name: GitHub Pages
    description: The browser-based converter is hosted on GitHub Pages from the cr0hn/LAPIS repository at https://cr0hn.github.io/LAPIS/,
      making it accessible without local installation or API keys.
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com