---

name: sdk-and-api-clients description: "Integrate with Langflow through REST APIs, OpenAPI contracts, Python SDK clients, streaming runs, and flow/project push-pull workflows." disable-model-invocation: true metadata: disco-role: operating license: MIT

SDK And API Clients

Use this sub-skill when the task is to call a Langflow server from application code, validate API examples, inspect OpenAPI contracts, normalize flow JSON for source control, or debug client-side API failures.

Route elsewhere when the user wants local flow execution with lfx run or lfx serve (../executor-cli/SKILL.md), backend route/service implementation (../backend-runtime/SKILL.md), flow JSON authoring semantics (../flow-authoring/SKILL.md), or deployment and server configuration (../deployment-and-operations/SKILL.md).

Fast Start

1. Use references/sdk-reference.md for Python SDK construction, sync/async clients, CRUD, run/stream helpers, push/pull, environment config, and typed exceptions.
2. Use references/api-contracts.md for REST endpoint shapes, OpenAPI files, streaming event contracts, TypeScript client notes, and API example validation strategy.
3. Use references/troubleshooting.md for install/import errors, auth and HTTP failures, streaming edge cases, schema problems, normalization surprises, and backend-boundary signals.
4. Run scripts/normalize_flow_file.py when a flow JSON file must be made deterministic and safe for git before review or push.

Common Workflows

• Construct a Python client: prefer from langflow_sdk import Client, AsyncClient; pass base_url, optional api_key, and optional timeout. Use context managers (with Client(...) as client: or async with AsyncClient(...) as client:) when the client owns its HTTP transport.
• Run a flow: call client.run(flow_id_or_endpoint, input_value="...") for the simple case, or client.run_flow(flow_id_or_endpoint, RunRequest(...)) when setting input_type, output_type, tweaks, or stream explicitly.
• Stream a flow: iterate client.stream(...) or async for chunk in client.stream(...); handle chunk.is_token, chunk.is_end, and chunk.is_error, and map LangflowAuthError/LangflowHTTPError separately from event-level failures.
• Manage flows and projects: use list_flows, get_flow, create_flow, update_flow, upsert_flow, delete_flow, list_projects, download_project, and upload_project; push/pull wrap file-based flow upsert and normalized download.
• Normalize a flow file: run python scripts/normalize_flow_file.py flow.json --output flow.normalized.json --code-as-lines to strip secrets and volatile UI/server fields with deterministic JSON output.

Validation Checklist

• Verify the target server URL includes scheme and port, for example http://localhost:7860, and does not include trailing API path segments.
• Verify API keys are passed as x-api-key through SDK api_key or explicit HTTP headers; do not embed real keys in examples or committed TOML.
• For write operations, validate IDs and payloads with SDK models (FlowCreate, FlowUpdate, ProjectCreate, RunRequest) before sending.
• For streaming clients, assert non-2xx HTTP statuses raise typed SDK exceptions before parsing stream chunks, and assert final end chunks are optional in error paths.
• For OpenAPI or docs examples, prefer offline schema/example linting first; only run live examples against an intentionally started local or test Langflow instance.

References And Helpers

• SDK reference
• API contracts
• Troubleshooting
• Flow normalization helper