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Legora vs Sierrawhich AI research agent should you pick in 2026?

Collaborative legal AI agents for due diligence, contract review, and drafting.

🔬ResearchSemi-autonomousSubscription
Tool useMemoryRAGMulti-agent

Branded customer-facing agents from the founders of Salesforce + Google.

🎧SupportAutonomousSubscription
VoiceTool useMemoryRAG

Legora vs Sierra — specs

SpecLegoraSierra
Agent Rank58 / 100 (B)78 / 100 (A)
AutonomySemi-autonomousAutonomous
PricingSubscriptionSubscription · Free tier
Open sourceNoNo
CapabilitiesTool use, Memory, RAG, Multi-agentVoice, Tool use, Memory, RAG
Integrations4 apps3 apps
VerifiedVerified
ReleasedAug 2025Feb 2025

Categories: LegoraResearch · SierraSupport

Agent Rank breakdown

Legora
Agent Rank
58/ 100
BB-tier
自律性
8
機能
8
連携
2
料金
4
完成度
7
検証性
6

自律性、機能、連携、料金、成熟度、編集部の検証を基に自動算出。デプロイごとに更新されます。 どのように算出されているか?

Sierra
Agent Rank
78/ 100
AA-tier
自律性
9
機能
8
連携
6
料金
9
完成度
5
検証性
10

自律性、機能、連携、料金、成熟度、編集部の検証を基に自動算出。デプロイごとに更新されます。 どのように算出されているか?

Pros & cons

Legora
メリット
  • +$5.55B valuation Series D Apr 2026 — largest legal-AI Series D in history
  • +Multi-agent collaboration (different agents for different transaction types)
  • +Strong UK/EU foothold with Magic Circle firm adoption
デメリット
  • Newer than Harvey in US market — fewer NYC AmLaw 100 case studies
  • Enterprise pricing only — no associate-level self-serve
  • Best suited for transactional law (M&A, finance) — less for litigation
Sierra
メリット
  • +Best-in-class for branded customer-facing agents (voice + chat parity)
  • +Concierge onboarding from one of the strongest teams in AI
  • +Indistinguishable-from-human quality in tier-1 deployments
デメリット
  • Enterprise-only pricing — typical contracts $150–500k/year
  • Deployment is white-glove, not SaaS — multi-week setup
  • Overkill for SMB or mid-market support volumes

Pricing

Legora
Standard
カスタム
Boutique firms
  • +Contract review agent
  • +Due diligence
  • +Word + SharePoint
おすすめ
Enterprise
カスタム
Mid + large firms
  • +Multi-agent workflows
  • +iManage/NetDocs sync
  • +Advanced security
Sovereign
カスタム
Magic Circle
  • +EU/US/UK data residency
  • +BYO LLM option
  • +Dedicated tenants
Sierra
おすすめ
Branded agent
カスタム
Enterprise
  • +Voice + chat
  • +Custom persona
  • +White-glove implementation
  • +SOC 2 II + HIPAA option

Which one should you pick?

Legora

Pick Legora if its specific capabilities (Tool use, Memory) match what you need.

Try Legora →
Sierra

Pick Sierra if cost is the main constraint or if you want the highest autonomy and the verification loop is in place.

Try Sierra →

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Frequently asked

Should I pick Legora or Sierra in 2026?+

Pick Legora if its specific capabilities (Tool use, Memory) match what you need. Pick Sierra if cost is the main constraint or if you want the highest autonomy and the verification loop is in place. Most working teams running both can use Legora for primary work and Sierra for the workflows where its specific strengths matter.

What's the price difference between Legora and Sierra?+

Legora starts at Subscription; Sierra starts at Subscription · Free tier. Sierra is the cheaper entry option. For team deployments the TCO can differ — use the AI Agent Rank TCO calculator for your specific volume.

Which is more autonomous, Legora or Sierra?+

Sierra is the more autonomous of the two (Autonomous vs Semi-autonomous). Higher autonomy ships throughput faster but requires verification loops in place — see our autonomous-vs-copilot framing for when each tier wins.

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Want the real monthly cost at your volume? Run the TCO calculator →
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Legora vs Sierra (2026): which AI research agent wins? · AI Agent Rank