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4.4/5.0
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Psi

A portable, extensible, and open-source coding agent written in C and Lua.

Pricing

$0/mo

Free
Score

4.4/5

License
MIT
Last technical review
2026-11-08
Available plansVisit website (opens in a new tab)

Technical Overview

Psi is a portable, extensible coding agent designed for the terminal. It features a lightweight ANSI C core and a Lua runtime, allowing developers to use their choice of models. Licensed under MIT, it is fully open source and compatible with Linux, macOS, Windows, and more.

Analyst Evaluation: Pros and Limitations

Verified Advantages

  • Extremely lightweight portable binary of 6.4 MB.
  • Extensible architecture powered by a C core and Lua runtime.
  • Fully open source under the MIT license for complete auditability.

Technical Considerations

  • Lacks built-in multi-user management features.
  • Requires terminal proficiency and manual configuration for advanced workflows.

Technical Capabilities & Features

3/7
Included:REST & GraphQL API
Not available:SSO / SAML Authentication
Included:Self-Hosted Option
Included:Full Data Export
Not available:Role-Based Access Control (RBAC)
Not available:Custom Domains & SSL
Not available:Immutable Audit Logs
Scorecard
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Technical Scorecard: Psi

86/100
DX & Tech Documentation
Excellent
85/100
Pricing Fairness
Excellent
100/100
Security & Governance
Excellent
80/100
Data Portability & Sovereignty
Excellent
90/100
Performance & Reliability
Favorable
75/100

Time to Value & Fit by Segment: Psi

Estimated Time-to-Value< 1 hour (Immediate)

Near-instantaneous deployment with minimal technical friction.

Learning CurveModerate (Standard)

Requires consulting technical documentation and basic credentials setup.

Fit Index by Organization Size

Startup & Agile Teams1 to 50 members
80%
Mid-Market & Scaleup50 to 500 members
70%
Corporate Enterprise500+ members
50%
Pricing & TCO
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Pricing

$0.00/mo

Model: FREE.

Free Tier Verification:

  • No credit card required
  • Commercial use allowed
  • Unlimited usage with no expiration
  • No mandatory watermarks
Get Psi (opens in a new tab)

Billing Risks & Hidden Clauses: Psi

Free Tier Limits:

Completely free and open source under the MIT license with no usage limitations.

Total Cost of Ownership (TCO) Projection: Psi$0.00/mo
Deterministic cost estimation at 12 and 36 months based on team size, including SSO tax premiums and annual prepay discounts.
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Licensing Cost (1 to 100+ seats)
$0/forever
Unlimited team members with zero penalties
SSO Tax (SAML Enterprise)
$0no surcharge
No artificial security barriers
3-Year Investment (Software TCO)
$0total
operates under a zero-cost or open-source model. Licensing TCO is identical:
Usage Surcharges & Bill Shock Simulator: PsiWhat usage costs as you scale
Detect overage penalties before they impact engineering budget.
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Prototype / MVP (10 GB)

Included base quota in plan: 10 GB.
Low Risk / Predictable Bill
Base Monthly Rate
$0/mo
Fixed subscription or contracted tier
Overage Penalty
$0/month extra
Usage covered within plan quota
Estimated Monthly Invoice
$0/mo
Total monthly cost before taxes
Technical Mitigation Recommendation:

Suitable for development; verify concurrent connection limits.

Base Production (50 GB)

Included base quota in plan: 50 GB.
Low Risk / Predictable Bill
Base Monthly Rate
$0/mo
Fixed subscription or contracted tier
Overage Penalty
$0/month extra
Usage covered within plan quota
Estimated Monthly Invoice
$0/mo
Total monthly cost before taxes
Technical Mitigation Recommendation:

Implement table compression policies and temporal partitioning.

Active Growth (250 GB)

Included base quota in plan: 250 GB.
Low Risk / Predictable Bill
Base Monthly Rate
$0/mo
Fixed subscription or contracted tier
Overage Penalty
$0/month extra
Usage covered within plan quota
Estimated Monthly Invoice
$0/mo
Total monthly cost before taxes
Technical Mitigation Recommendation:

Offload cold backups to standard object storage (S3).

Large Scale (1.000 GB (1 TB))

Included base quota in plan: 1,000 GB.
Low Risk / Predictable Bill
Base Monthly Rate
$0/mo
Fixed subscription or contracted tier
Overage Penalty
$0/month extra
Usage covered within plan quota
Estimated Monthly Invoice
$0/mo
Total monthly cost before taxes
Technical Mitigation Recommendation:

Migrate to dedicated instance or self-hosted cluster to curtail I/O fees.

Security & Data Exit
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Compliance & Security Standards: Psi

SOC 2 Type IINot reported
ISO 27001Not reported
GDPR / RGPDNot reported
HIPAANot reported
PCI-DSSNot reported
Jurisdiction & Legal Sovereignty
🇺🇸United States [US]Immune to US CLOUD Act (EU Sovereign)DPA On Request
SSO Availability (SAML Enterprise)
No SSO Documented
Data Residency
SELF_HOSTED
AI Privacy Policy
Not evaluated
Data Liberation & Migration Runbook: PsiJSON · TXT
Actionable escape runbook and credential export guarantees to mitigate vendor lock-in.
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Supported Structured Export Formats
JSONTXT
Password Hash Portability
Locked: Proprietary Algorithm / No Export

Credential hashes are guarded under proprietary algorithms and cannot be exported.

CLI Command / Rescue Endpoint
git clone / rm binary
Exit Protocol & Migration Notes

Al ser un software de código abierto y local, no requiere migración de datos compleja.

Deployment & Infrastructure Requirements: PsiMIT
Hardware specs and Docker directives to run on local servers, dedicated VPS, or Kubernetes without telemetry leak to the cloud.
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Minimum Memory1 GB RAM (Recommended)
Compute CPU1 vCPU
Runtime / LanguageLua
Code LicenseMIT
Docker CLI Directive
docker run -d --name psi -p 8080:8080 psi:latest
Companion Services & Dependencies:
PostgreSQL 15+Redis 7+
Community & Repository
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Technical Reputation of Psi

83/100 Technical Trust

Frequent Praises in Production

  • Extremely lightweight portable binary of 6.4 MB.
  • Extensible architecture powered by a C core and Lua runtime.
  • Fully open source under the MIT license for complete auditability.

Reported Production Frictions

  • Lacks built-in multi-user management features.
  • Requires terminal proficiency and manual configuration for advanced workflows.
Commercial Treatment & Vendor Lock-in:1-Click Cancellation

Immediate cancellation from account settings without phone calls or forced retention.

Open source repository activity: Psi6
Stars, forks and release cadence
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Stars6
Forks0
Open Issues24
SPDX LicenseMIT
Latest Commit DetectedNov 8, 2026

Frequently Asked Technical Questions (Psi)

What operating systems are supported?

Psi runs natively on Linux, macOS, Windows, FreeBSD, OpenBSD, Haiku, and other Unix-like or compatible environments.

How are features and commands extended?

Agent behaviors, commands, and interfaces can be written, customized, and reloaded dynamically using Lua extensions.

What is the software license?

Psi is released as open source under the MIT license, permitting broad usage, modification, and redistribution.

Direct Alternatives

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