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
51.8/100 developing ▬ flat Agent 69/100 agent native Full breakdown ↓
scored 2026-07-27 · rubric v0.5
AccessSelf serve
13 APIs 1 MCP Servers
CompanyDataETLELTReverse ETLData PipelinesData IntegrationChange Data CaptureTransformationsAnalyticsMCPAI Agents

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5
Composite quality — 51.8/100 · developing
Contract Quality 14.2 / 25
Developer Ergonomics 13.5 / 20
Commercial Clarity 12.1 / 20
Operational Transparency 2.1 / 13
Governance 0.0 / 12
Discoverability 10.0 / 10
Agent readiness — 69/100 · agent native
Machine-Readable Contract 18 / 18
Agentic Access Contract 15 / 15
MCP Server 12 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 8 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 0 / 7
Typed Event Surface 0 / 6
Agent Skills 5 / 5
Well-Known Catalog 4 / 4
Consent & Bot Identity 0 / 3
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. 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. Want it done for you? Prioritized profiling — $2,500 →

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

MCP Servers 1

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

weld-mcp.yml

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
AgenticAccess
 MCPServer
MCPServer
 AgentSkill
AgentSkill
 LLMsTxt
LLMsTxt
 WellKnown
WellKnown

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Conventions
Conventions
 ErrorCatalog
ErrorCatalog
 Lifecycle
Lifecycle
 Conformance
Conformance
 DataModel
DataModel

Access & Security 4

Authentication, authorization, and security posture

TrustCenter
TrustCenter
 DomainSecurity
DomainSecurity
 Authentication
Authentication
 Compliance
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)

apis.yml Raw ↑ 
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.
accessModel:
  pricing: unknown
  onboarding: self-serve
  trial: false
  try_now: false
  public: false
  label: Self-serve signup
  confidence: medium
  source:
  - authentication
  generated: '2026-07-22'
  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: '0.20'
created: '2026-07-17'
modified: '2026-07-21'
tags:
- 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:
  - 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