Weld

Weld is a programmable data-infrastructure platform for moving and transforming data. It runs near real-time ELT/ETL pipelines from 300+ prebuilt connectors, log-based Change Data Capture (CDC), SQL-based data transformations with lineage and version history, and Reverse ETL to activate modeled data back into operational tools. The Weld Connect REST API and a hosted Model Context Protocol (MCP) server let developers and AI agents create connections, run and monitor ELT syncs, build and publish transforms, and orchestrate pipelines programmatically. Weld is a Copenhagen-based company backed by a16z and other leading investors.

Weld publishes 13 APIs on the APIs.io network, including Connection Bridge API, Connections API, Custom Reports API, and 10 more. Tagged areas include Company, Data, ETL, ELT, and Reverse ETL.

Weld’s developer surface includes authentication, documentation, API reference, getting-started guide, engineering blog, pricing, support, and 21 more developer resources.

🌐 Visit website 📡 Source on GitHub

44.7/100 developing ▬ flat Agent 37/100 agent ready saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

1 APIs 1 MCP Servers

Company Data ETL ELT Reverse ETL Data Pipeline Data Integration Change Data Capture Transformation Analytics MCP AI Agents

Kin Score

Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0

Composite quality — 44.7/100 · developing

Contract Quality 12.6 / 23

Developer Ergonomics 10.6 / 18

Access Clarity 8.5 / 18

Operational Transparency 1.8 / 12

Contract Governance 0.5 / 11

Discoverability 6.8 / 9

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 37/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 6 / 6

MCP Server 12 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/weld: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 13

Individual APIs this provider publishes, each with its own machine-readable definition.

Weld Connection Bridge API

The Connection Bridge API from Weld — 1 operation(s) for connection bridge.

Weld Connections API

The Connections API from Weld — 3 operation(s) for connections.

Weld Custom Reports API

The Custom Reports API from Weld — 1 operation(s) for custom reports.

Weld ELT Stream Runs API

The ELT Stream Runs API from Weld — 2 operation(s) for elt stream runs.

Weld ELT Streams API

The ELT Streams API from Weld — 5 operation(s) for elt streams.

Weld ELT Syncs API

The ELT Syncs API from Weld — 8 operation(s) for elt syncs.

Weld Integrations API

The Integrations API from Weld — 1 operation(s) for integrations.

Weld Orchestration Runs API

The Orchestration Runs API from Weld — 2 operation(s) for orchestration runs.

Weld Orchestrations API

The Orchestrations API from Weld — 3 operation(s) for orchestrations.

Weld Reverse ETL Failed Records API

The Reverse ETL Failed Records API from Weld — 4 operation(s) for reverse etl failed records.

Weld Reverse ETL Sync Runs API

The Reverse ETL Sync Runs API from Weld — 2 operation(s) for reverse etl sync runs.

Weld Reverse ETL Syncs API

The Reverse ETL Syncs API from Weld — 9 operation(s) for reverse etl syncs.

Weld Transforms API

The Transforms API from Weld — 11 operation(s) for transforms.

Scroll for all 13

Open Collections 14

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

Weld REST Connection Bridge API

OPEN COLLECTION

Weld REST Connection Bridge Connections API

OPEN COLLECTION

Weld REST Connection Bridge Custom Reports API

OPEN COLLECTION

Weld REST Connection Bridge ELT Stream Runs API

OPEN COLLECTION

Weld REST Connection Bridge ELT Streams API

OPEN COLLECTION

Weld REST Connection Bridge ELT Syncs API

OPEN COLLECTION

Weld REST Connection Bridge Integrations API

OPEN COLLECTION

Weld REST Connection Bridge Orchestration Runs API

OPEN COLLECTION

Weld REST Connection Bridge Orchestrations API

OPEN COLLECTION

Weld REST Connection Bridge Reverse ETL Failed Records API

OPEN COLLECTION

Weld REST Connection Bridge Reverse ETL Sync Runs API

OPEN COLLECTION

Weld REST Connection Bridge Reverse ETL Syncs API

OPEN COLLECTION

Weld REST Connection Bridge Transforms API

OPEN COLLECTION

Scroll for all 14

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

Weld MCP Server

Official hosted Weld MCP server. Lets AI assistants (Claude Desktop, claude.ai, Claude Code, Cursor, GitHub Copilot, Windsurf, and other MCP clients) interact directly with a We...

MCP SERVER

Security Posture 3

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Weld Authentication

apiKey · 1 scheme

SECURITY

Weld Domain Security

TLSv1.2 · HSTS · DMARC

SECURITY

Weld Trust Center

SOC 2, ISO 27001, GDPR

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Weld Agentic Access

65 operations · 33 acting · 33 human-in-the-loop

65 operations · 33 acting

AGENTIC

Resources

Get Started 3

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

SignUp

SignUp

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 5

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

MCPServer

AgentSkill

LLMsTxt

WellKnown

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Conventions

ErrorCatalog

Lifecycle

Conformance

DataModel

Access & Security 4

Authentication, authorization, and security posture

TrustCenter

DomainSecurity

Authentication

Compliance

Operate 3

Status, limits, changes, and where to get help

SLA

SLA

Support

Support

StatusPage

StatusPage

Commercial 3

Pricing, plans, and the legal terms of use

Pricing

Pricing

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 2

The organization behind the API

Blog

Blog

Website

Website

Other 1

Properties that don't map to a standard resource type

Overlay

Overlay

Source (apis.yml)

aid: weld
name: Weld
description: Weld is a programmable data-infrastructure platform for moving and transforming data. It runs near real-time
  ELT/ETL pipelines from 300+ prebuilt connectors, log-based Change Data Capture (CDC), SQL-based data transformations with
  lineage and version history, and Reverse ETL to activate modeled data back into operational tools. The Weld Connect REST
  API and a hosted Model Context Protocol (MCP) server let developers and AI agents create connections, run and monitor ELT
  syncs, build and publish transforms, and orchestrate pipelines programmatically. Weld is a Copenhagen-based company backed
  by a16z and other leading investors.
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - security
  generated: '2026-09-03'
  method: derived
image: https://weld.app/opengraph-image.png
url: https://raw.githubusercontent.com/api-evangelist/weld/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- a16z
x-tier: profiled
x-tier-reason: enriched-from-portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-21'
tags:
- Company
- Data
- ETL
- ELT
- Reverse ETL
- Data Pipeline
- Data Integration
- Change Data Capture
- Transformation
- Analytics
- MCP
- AI Agents
tags_raw:
- Company
- Data
- ETL
- ELT
- Reverse ETL
- Data Pipelines
- Data Integration
- Change Data Capture
- Transformations
- Analytics
- MCP
- AI Agents
apis:
- aid: weld:weld-connection-bridge-api
  name: Weld Connection Bridge API
  description: The Connection Bridge API from Weld — 1 operation(s) for connection bridge.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - Connection Bridge
  properties:
  - type: OpenAPI
    url: openapi/weld-connection-bridge-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-connections-api
  name: Weld Connections API
  description: The Connections API from Weld — 3 operation(s) for connections.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - Connections
  properties:
  - type: OpenAPI
    url: openapi/weld-connections-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-custom-reports-api
  name: Weld Custom Reports API
  description: The Custom Reports API from Weld — 1 operation(s) for custom reports.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - Custom Reports
  properties:
  - type: OpenAPI
    url: openapi/weld-custom-reports-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-elt-stream-runs-api
  name: Weld ELT Stream Runs API
  description: The ELT Stream Runs API from Weld — 2 operation(s) for elt stream runs.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - ELT Stream Runs
  properties:
  - type: OpenAPI
    url: openapi/weld-elt-stream-runs-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-elt-streams-api
  name: Weld ELT Streams API
  description: The ELT Streams API from Weld — 5 operation(s) for elt streams.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - ELT Streams
  properties:
  - type: OpenAPI
    url: openapi/weld-elt-streams-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-elt-syncs-api
  name: Weld ELT Syncs API
  description: The ELT Syncs API from Weld — 8 operation(s) for elt syncs.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - ELT Syncs
  properties:
  - type: OpenAPI
    url: openapi/weld-elt-syncs-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-integrations-api
  name: Weld Integrations API
  description: The Integrations API from Weld — 1 operation(s) for integrations.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - Integration
  tags_raw:
  - Integrations
  properties:
  - type: OpenAPI
    url: openapi/weld-integrations-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-orchestration-runs-api
  name: Weld Orchestration Runs API
  description: The Orchestration Runs API from Weld — 2 operation(s) for orchestration runs.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - Orchestration Runs
  properties:
  - type: OpenAPI
    url: openapi/weld-orchestration-runs-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-orchestrations-api
  name: Weld Orchestrations API
  description: The Orchestrations API from Weld — 3 operation(s) for orchestrations.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - Orchestrations
  properties:
  - type: OpenAPI
    url: openapi/weld-orchestrations-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-reverse-etl-failed-records-api
  name: Weld Reverse ETL Failed Records API
  description: The Reverse ETL Failed Records API from Weld — 4 operation(s) for reverse etl failed records.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - Reverse ETL Failed Records
  properties:
  - type: OpenAPI
    url: openapi/weld-reverse-etl-failed-records-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-reverse-etl-sync-runs-api
  name: Weld Reverse ETL Sync Runs API
  description: The Reverse ETL Sync Runs API from Weld — 2 operation(s) for reverse etl sync runs.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - Reverse ETL Sync Runs
  properties:
  - type: OpenAPI
    url: openapi/weld-reverse-etl-sync-runs-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-reverse-etl-syncs-api
  name: Weld Reverse ETL Syncs API
  description: The Reverse ETL Syncs API from Weld — 9 operation(s) for reverse etl syncs.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - Reverse ETL Syncs
  properties:
  - type: OpenAPI
    url: openapi/weld-reverse-etl-syncs-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
- aid: weld:weld-transforms-api
  name: Weld Transforms API
  description: The Transforms API from Weld — 11 operation(s) for transforms.
  humanURL: https://weld.app/docs/api-reference
  baseURL: https://connect.weld.app
  tags:
  - Transforms
  properties:
  - type: OpenAPI
    url: openapi/weld-transforms-api-openapi.yml
  - type: Documentation
    url: https://weld.app/docs/api-reference
  - type: GettingStarted
    url: https://weld.app/docs/weld-connect/getting-started
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: TrustCenter
  url: security/weld-trust-center.yml
- type: DomainSecurity
  url: security/weld-domain-security.yml
- type: AgenticAccess
  url: agentic-access/weld-agentic-access.yml
- type: Authentication
  url: authentication/weld-authentication.yml
- type: MCPServer
  url: mcp/weld-mcp.yml
- type: Conventions
  url: conventions/weld-conventions.yml
- type: ErrorCatalog
  url: errors/weld-problem-types.yml
- type: Lifecycle
  url: lifecycle/weld-lifecycle.yml
- type: Conformance
  url: conformance/weld-conformance.yml
- type: Compliance
  url: https://weld.app/security
- type: DataModel
  url: data-model/weld-data-model.yml
- type: AgentSkill
  url: skills/_index.yml
- type: Overlay
  url: overlays/weld-connect-overlay.yaml
- type: LLMsTxt
  url: llms/weld-llms.txt
- type: WellKnown
  url: well-known/weld-well-known.yml
- type: SLA
  url: https://weld.app/service-level-agreement
- type: DeveloperPortal
  url: https://weld.app/docs
- type: Documentation
  url: https://weld.app/docs
- type: APIReference
  url: https://weld.app/docs/api-reference
- type: GettingStarted
  url: https://weld.app/docs/weld-connect/getting-started
- type: Blog
  url: https://weld.app/blog
- type: Pricing
  url: https://weld.app/pricing
- type: Support
  url: https://weld.app/support
- type: SignUp
  url: https://workspace.weld.app/signup
- type: TermsOfService
  url: https://weld.app/terms-of-service
- type: PrivacyPolicy
  url: https://weld.app/privacy-policy
- type: StatusPage
  url: https://status.weld.app/
- type: Website
  url: https://weld.app
x-enrichment:
  date: '2026-07-21'
  status: enriched
  artifacts_added: 18
  pass: local-v1

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