Letta vs StackAI

Comprehensive side-by-side comparison — features, pricing, performance, and more.

Data last refreshed October 2026

Letta

Machines that learn — self-improving AI agents (from the creators of MemGPT)

Open Source

78% verification coverage

StackAI

Stack AI (Eigen Inc.)

AI Agents for the Enterprise

Freemium

75% verification coverage

Trust & Reliability

Letta

Uptime:99.96% (365-day)Status page

Customers (per vendor):Bilt, 11x, Kognitos +1

GDPR

StackAI

Uptime:100.0%Status page

Customers (per vendor):BAE Systems, Mayo Clinic, MIT +7

GDPR

SOC 2

HIPAA

Overall Winner: StackAI

6.7/10 vs Letta at 5.8/10

Leads in:

Integration

Compliance & Data Protection

Ease of Use

Scores are AI-estimated from publicly available data — not an independent test or a verified user rating. How we rank →

AI Comparison Summary

Letta

5.8

avg score

StackAI

6.7

avg score

StackAI leads overall — particularly in Ease of Use and Integration and 1 more.

Based on 6 dimensions

Scores are AI-estimated from publicly available data — not an independent test or a verified user rating. How we rank →

Overall Winner

StackAI

6.7 / 10

Letta

Best For

Developers building AI agents for automated workloads

Teams creating custom agents with shared resources and permissions

Individuals using stateful agents for personal use

Enterprises requiring high-volume agent deployments with custom pricing

StackAI

Best For

IT teams orchestrating AI across the enterprise

Organizations with regulated and complex operations

Legal teams redlining contracts and accelerating due diligence

Risk and compliance teams strengthening defense with AI

* Verdict is based on our algorithmic scoring of publicly available data. Learn about our methodology

Letta is best for

✍️Writing & Content8.0💬Chat & Conversation8.0🤖Automation & Agents7.1

StackAI is best for

💬Chat & Conversation7.3💻Coding & Dev7.0🤖Automation & Agents7.0

Filter by your use case:

Limitations

Letta

Cons

Free plan is limited to 3 stateful agents
Personal Plans require OAuth authentication
Developer Plans use API key authentication
Tool execution on the API Plan is usage-based
Letta Auto usage is quota-limited on Pro plans
Data collection for hosted services may be used for model training

StackAI

Cons

No cons listed yet.

Weighted Score — Adjust What Matters to You

Pick a profile or drag sliders — scores and radar update instantly on the right.

Quick profiles:

Ease of Use5

Customization5

Support5

Integration5

Compliance & Data Protection5

Performance5

Planning Quality5

Dimension Comparison

Letta

5.8

/ 10

StackAI

6.7

/ 10

Your pick

Dimension Breakdown

Ease of Use

How intuitive is onboarding, UI navigation, and day-to-day usage for the target audience?

Letta

1.0

StackAI

3.0▲ +2.0

Customization

Calculated

How much can users tailor workflows, settings, prompts, or outputs to their needs?

Letta

9.0▲ +1.0

StackAI

8.0

Support

How strong is the documentation, customer support, community, and learning resources?

Letta

10.0▲ +1.0

StackAI

9.0

Integration

Calculated

How well does it connect with other tools, APIs, and workflows?

Letta

7.0

StackAI

9.0▲ +2.0

Compliance & Data Protection

Calculated

Compliance certifications and data-protection posture, counted from ten verified signals: SOC 2 Type II, GDPR compliance, HIPAA, WCAG AA/AAA, PII redaction, licensed-only training, a published sub-processor list, a downloadable DPA, not training on user data, and a documented deletion path

Letta

3.0

StackAI

6.0▲ +3.0

Performance

Calculated

Latency + throughput speed

Letta

5.0

StackAI

5.0

Planning Quality

Calculated

Multi-step planning depth + replanning capability

Letta

—

StackAI

—

Calculated = derived from structured signals (integration count, API/open-source config, compliance certs, response-time). AI = LLM-assessed from public website content. Methodology

Task Performance

Letta

Task

StackAI

8.0

Role Definition

7.0

8.0

Task Decomposition

6.0

7.0

Agent Coordination

6.0

Inter Agent Communication

5.0

7.0

Workflow Orchestration

9.0

7.0

Tool Use Delegation

7.0

9.0

State Management

6.0

5.0

Error Recovery

6.0

5.0

Observability

8.0

Scalability Throughput

7.0

6.0

Workflow Building

9.0

6.0

Trigger Variety

8.0

* Task scores (1–10) are algorithmically generated from publicly available data.

Data is sourced from public information and vendor websites. It may not always be up-to-date — verify pricing and features directly with the vendor before purchasing.Report inaccuracy

Frequently Asked Questions

What are the main differences between Letta and StackAI?

Letta — "Machines that learn — self-improving AI agents (from the creators of MemGPT)". StackAI — "AI Agents for the Enterprise". The Features section on this page compares them side by side.

Who is Letta best for compared with StackAI?

Letta is best for Developers building AI agents for automated workloads; and for Teams creating custom agents with shared resources and permissions. StackAI is best for IT teams orchestrating AI across the enterprise; and for Organizations with regulated and complex operations.

How does the pricing of Letta compare with StackAI?

Letta is open source, includes a free plan, paid plans start at $20/month. StackAI is freemium, includes a free plan. Always verify current pricing with the vendor.

Does Letta or StackAI have a free plan?

Letta is open source. StackAI has a free plan. Always verify current pricing with the vendor.

Do Letta and StackAI offer an API?

Letta offers a public API. StackAI offers a public API.

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