18.7
Vellum describes itself as a personal AI assistant that can read files, manage calendars, send email, run code, and control a computer.
Free planOpen sourceAndroidiOSWeb
Best Tool Calling in 2026
Tool-calling software connects an AI model with external tools, APIs or workflows so it can request actions and structured results. This chart helps compare options for building, routing or supervising those calls. Check deployment, protocol support, authentication and observability before choosing. If you need phone access, confirm Android support with the maker; listed platform options include web, API,…
28.4
Dify is an open-source platform for building AI applications with workflows, knowledge retrieval, model management, observability, and tools.
Free planOpen sourceWebAPIExtension
38.3
Inngest orchestrates asynchronous code as durable functions for event-driven workflows, background jobs, and agents.
Free planOpen sourceWebAPILinux
- 4
Liner
Liner combines AI search, academic research, and writing tools for professional workflows.
Free planAndroidiOSWebAPI8.1From $14.99 a month - 5
Rasa
Free planOpen sourceWebAPILinuxmacOS7.8Free plan - 6
agentgateway
Agentgateway is a free, open-source HTTP and gRPC gateway for routing, securing, observing, and governing traffic involving services, LLMs, MCP, and…
Free planOpen sourceWebAPILinuxmacOS7.5Free plan - 7
LLM Gateway
LLM Gateway gives product and platform teams one OpenAI-compatible API for routing requests across more than 250 models from over 40 providers.
Free planOpen sourceWebAPIExtensionLinux7.4Free plan - 8
Flowise
Flowise is an open-source platform for building generative AI agents and workflows based on large language models.
Free planWebAPILinuxmacOS7.2From $35 a month - 9
Pipedream
Pipedream is an integration layer for AI agents that provides managed authentication and tools across thousands of APIs.
Free planWebAPI7.0From $99 a month - 10
Kore.ai
WebAPISelf-hosted6.5 - 11
n8n
n8n is a workflow automation platform for connecting services and APIs, with multi-step workflows and conditional logic.
Self-hosted6.5From €20 a month - 12
Inference Gateway
Inference Gateway is a free, open-source cloud-native proxy that presents hosted and local language-model providers through one OpenAI-compatible API.
WebAPILinuxmacOS6.2 - 13
Langflow
Langflow is a free, open-source Python framework for building customizable AI applications, including agent and MCP applications.
WebAPILinuxmacOS6.2 - 14
Google Cloud API Gateway
Google Cloud API Gateway provides a managed entry point for backend services, presenting them through a consistent REST API.
WebAPI6.1From $1.50 a month - 15
Gravitee API Management
WebLinuxWindows5.9From $2,500 a month - 16
5.6From $0.01 a month - 17
5.1 - 18
MCP Gateway
Web4.6 - 19
Santeon
Web4.6 - 20
Toolhouse
Web4.6 - 21
ToolRoute
Web4.6
Choosing well
Match the deployment
Choose between web access, an API, self-hosting or desktop platforms according to where your workflows run. Windows, macOS and Linux support can matter for local development or operations.
For a phone workflow, verify Android support directly. The platform list for this category does not state Android availability.
Check free and paid terms
A free plan can help you evaluate a tool before committing. Pricing notes range from free plans to paid starting prices, while a free trial may be offered instead.
Read what the free plan includes and whether the paid price is recurring. Examples include Dify, Flowise and Inngest with free plans and paid tiers.
Compare call controls
Look at protocol support, tool-choice controls, parallel tool calls and structured outputs. These determine how precisely a workflow can select tools and handle returned data.
Authentication methods and call observability are useful checks when requests need access controls or a clear record of activity.
Review code and hosting
Open-source code is available from tools in this category, but licences and hosting models differ. Check the tool's licence before changing or redistributing code.
Self-hosting can give you control over deployment, while a hosted web or API option may reduce operational work.
Questions people ask
Do these tool-calling products have Android apps?
The platform notes list web, API, self-hosted, Windows, macOS and Linux. Check the product page for Android availability before relying on a phone workflow.
Can I start without paying?
A free plan is available from products in this category. Pricing and limits differ, so check the stated free-plan terms and paid starting price.
Are any options open source?
Open-source code is offered by products in this category. Review the licence and hosting requirements before using or modifying the code.
What should I compare besides price?
Compare protocol support, deployment, tool-choice control, parallel tool calls, structured outputs, authentication methods and call observability.
Do these tools offer trials?
A free trial is offered by products in this category, while others use a free plan or paid access. Check the product's current terms.