Best AI Agent Infrastructure Tools in 2026

1. Composio — best for authenticated tool calling

Composio is the layer that lets an agent actually do things: managed OAuth plus function calling across more than 1,000 apps, exposed either through an MIT-licensed SDK or an MCP server. It removes the part of agent-building teams consistently underestimate — storing, refreshing and scoping user credentials for every third-party API the agent touches. The hosted platform meters by tool call: 20,000 free a month, then $29/month for 200,000 and $229/month for 2 million. It ranks first because tool access is the capability most agents need and the one most likely to be built badly in-house. Two caveats: usage-based billing scales unpredictably, with premium tools such as search and sandboxes charging roughly 3x the standard rate, and Composio has announced that pricing changes on August 15, 2026, so today’s quotas may not hold.

2. Mem0 — best for agent memory

Mem0 gives an agent persistent memory — it extracts durable facts from a conversation, stores them, and retrieves the relevant ones next session, so the agent stops starting cold every time. The core is Apache-2.0 with more than 61,000 GitHub stars; the hosted platform adds a managed API and dashboard. The Hobby tier is free for 10,000 add requests and 1,000 retrievals a month, Starter is $19/month, Growth is $79/month and Pro is $249/month. It is the second layer most agent teams reach for, and its verified pricing is the freshest in this list. The caveat worth knowing before you build on it: graph memory, which links entities rather than storing loose facts, is gated to the $249/month Pro tier — a steep jump from $79 — and retrieval quotas run roughly ten times smaller than write quotas, so read-heavy agents hit the ceiling first.

3. E2B — best for running agent-written code

E2B gives an agent a real Linux box — terminal, filesystem, network, package installs — inside a Firecracker microVM that boots in under 200ms, so LLM-generated code executes somewhere that is not your production server. The Hobby tier is free with a one-time $100 credit, 1-hour sessions and 20 concurrent sandboxes; Pro is $150/month for 24-hour sessions and 100 concurrent sandboxes, with compute billed per second on top at roughly $0.05 per vCPU-hour. The SDK and infrastructure are Apache-2.0 and self-hostable, which is why it ranks above the hosted-only options for teams with a security review to pass. The caveat is the shape of the pricing: the $150/month Pro fee is a hard floor that lands before any usage, punishing spiky workloads, and there is no GPU offering on any tier.

4. Langfuse — best for tracing and evals

Langfuse is the observability layer: traces of every LLM call, prompt management, datasets and evaluation runs, so you can see why an agent did something rather than guessing from output. The core is MIT-licensed and every core feature is free when self-hosted — no capability gating — which makes it the best free pick in this list. Langfuse Cloud adds a free Hobby tier with 50,000 units a month, Core at $29/month and Pro at $199/month with SOC 2 reports and three-year retention. It is used by more than 2,300 companies and instruments agents built on any framework. Two honest limits: self-hosting is not a single container at production scale — it wants Postgres, ClickHouse and Redis or S3 — and some enterprise features including SCIM, audit logs and project-level RBAC sit behind the commercial licence despite the MIT core.

5. Browserbase — best for giving agents a browser

Browserbase runs headless Chrome sessions in the cloud on demand, so an agent can log into a site, click through a flow and read the result without you operating a browser fleet. It ships alongside Stagehand, its open-source automation framework, and handles the parts that break at scale: concurrency, proxies, session recording and stealth. The Free plan gives 1 browser hour and 3 concurrent browsers; Developer is $20/month for 100 browser hours then $0.12 per hour, and Startup is $99/month for 500 hours at $0.10 per hour. At $20/month it is the cheapest paid entry here. The caveat is inherent to the job rather than the vendor: browser automation is brittle, and a target site’s redesign breaks your flow no matter how good the infrastructure underneath it is.

6. Exa — best for grounding agents in live web data

Exa is an AI-native search API built for retrieval rather than for humans reading a results page — semantic search, full page-content extraction, and Websets for assembling structured collections of results. It is the layer that keeps an agent’s answers tied to something citable and current instead of to training data. The API includes 20,000 free requests a month and bills search from $7 per 1,000 requests; Websets runs free, $49/month or $449/month. It ranks last only because not every agent needs live web access, while every agent needs tools and most need memory. The caveat is price drift and stacking: standard search rose from $5 to $7 per 1,000 requests in early 2026, add-on charges compound, and the gap from $49 to $449 on Websets leaves nothing in between.

How we picked

We ranked the plumbing you add around an agent, layer by layer — authenticated tool calling, memory, code execution, observability, browser access and web grounding — choosing one strong tool per layer rather than six variations on the same job. Agent frameworks were deliberately excluded: LangChain, CrewAI, Dify, Flowise and OpenHands are how you build the agent, not what you run it on. So were vector databases and RAG-first frameworks, which serve retrieval rather than action, and general GPU and inference clouds such as Modal, Groq and Baseten, which host models rather than support agents specifically. We weighted whether the free tier is genuinely usable, whether the core is open source and self-hostable, and how predictable the metered pricing is. Pricing was verified against each vendor’s official pricing page between June 22 and July 18, 2026. No tool paid or provided incentives to appear, and placements cannot be bought.