Alternatives to Synth

Arena AI ranks chat models, coding agents and fullstack builds on live head-to-head human votes.

AppWorld is a simulated-world benchmark for evaluating AI coding agents across 9 apps and 457 APIs.

Imbue builds inspectable coding-agent tools, from mngr's parallel agent runner to Latchkey's HTTP permissions

Hermes Desktop is a free, open-source desktop GUI for the Hermes Agent — a self-hosted AI agent with a built-in learning loop that turns

Open-source benchmark that scores AI agents on real, multi-step software-company work tasks.

Open-source library of 817 structured cybersecurity skill files your AI coding agent loads on demand, mapped to MITRE ATT&CK and licensed Apache 2.0.

Self-hosted cloud development environments with built-in governance for AI coding agents and LLM traffic.

Paseo is a self-hosted control plane for running many coding agents at once — Claude Code, Codex, Copilot and 33+ more — from desktop,

DeerFlow is an open-source SuperAgent harness that researches, codes, and creates inside a persistent Docker sandbox.

Polymath builds simulation environments for training and evaluating autonomous AI agents on long-horizon, multi-tool work

Self-hosted layer that gives your AI coding agents shared memory, managed MCP tools, and cross-model audit.

Zhipu GLM is a full-stack large-model platform with open-weights GLM-5.3 coding models, MaaS APIs and autonomous agents.

LangSmith is agent and LLM observability: trace, monitor, and evaluate AI agents in cloud, BYOC, or self-hosted.

Google Antigravity runs parallel local coding agents across real codebases from $0/month.

Mastra is an open-source TypeScript agent framework for durable agents, typed workflows, and built-in evals.

Pipedream is the integration layer that gives AI agents managed auth plus 10,000+ tools across 3,000+ APIs.

Tessl is an agent enablement platform for versioning, scanning and evaluating the AI agent skills your coding agents run.

Open-source, self-hosted AI agent that plans tasks, runs tools, and grows its own long-term memory.

OMNI is a shell hook that compresses terminal output for coding agents and returns repeat reads as handles

Local, MIT-licensed token and cost observability for AI coding agents — reads the logs your agents already write.

Free, open-source web UI for prototyping multi-agent AI workflows on AutoGen AgentChat — build agent teams without writing code.

A free, MIT-licensed Python framework from OpenAI for building multi-agent workflows with handoffs, guardrails, and tracing.

Agent evaluation platform that simulates voice and chat agents, traces production, and scores hallucinations before customers hit them

Microsoft Agent Framework is a developer SDK for building agentic AI with tools, workflows, and a GA Agent Harness runtime.

SmolAgents is Hugging Face's open-source Python library for building code-writing AI agents in a few lines of code.

AgentScope is an open-source Python framework from Alibaba for building distributed multi-agent AI systems.

GitLab Duo adds policy-governed AI agents and flows across the DevSecOps lifecycle inside GitLab

Open-source, self-hosted agentic data assistant that connects to your databases, writes SQL and code, and runs analysis in sandboxes

Flowith is an infinite canvas for running parallel AI image, video, slide, and research agents at once.

Microsoft's open-source SDK for building AI agents and copilots with plugins, memory, and multi-agent orchestration.