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Lago — AI for General (Professional Services)

Automate complex billing for professional services, from retainers and project fees to usage-based consulting hours.

Lago is an open-source billing platform that handles hybrid pricing models, giving your firm transparency and control.

What is Lago?

Lago: Automate complex billing for professional services, from retainers and project fees to usage-based consulting hours. It has a free plan. Zekai's independent review scores it 8.5 out of 10. Best for automating complex, hybrid billing for services firms.

Facts checked 31 Oct 2026.

DifferentiatorOpen-source, API-first platform for any pricing model.
ProofUsed by Mistral AI; SOC 2 Type II compliant.
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Free Plan
Free plan verified · free AI tools for Consultants
8.5 Zekai
Flexible, complex billing automation.
AI for General (Professional Services)
Ease of Use
6.2
Accuracy
9.4
Value
9.4
Time Saving
9.0
Hybrid BillingUsage MeteringOpen SourceAPI FirstSOC 2 Compliant
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Zekai Verdict

What is it?
Lago is an open-source, API-first billing platform designed for professional services firms with complex revenue models.
Best for
Best for professional services firms needing to automate and scale complex, hybrid billing models that mix retainers…
Not ideal for
Requires engineering resources for initial setup and integration.
Price
Free plan
Zekai Score
8.5/10
Hand-scored by Zekai

Top AI for General (Professional Services) picks

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⚡ Quick answer

For professional services firms with complex client contracts, Lago is a leading AI-powered billing platform. Its strength lies in automating hybrid models that mix retainers, project fees, and usage-based billing, a common need in consulting and agencies. As an open-source, API-first solution with SOC 2 Type II compliance, it provides the flexibility and security required to manage sophisticated revenue streams.

CategoryBilling & Invoicing
Best forAutomating complex, hybrid billing for services firms.
Free planYes (self-hosted open-source)
DifferentiatorOpen-source, API-first platform for any pricing model.
ProofUsed by Mistral AI; SOC 2 Type II compliant.
Rating8.5/10
📖 About Lago
How It Works

Your workflow, automated

1
Model Your Pricing
Define all billable metrics, from fixed retainers to usage-based consulting hours, within Lago's flexible framework.
2
Integrate & Meter Usage
Use the API to send real-time usage events from your project management or time-tracking systems to Lago.
3
Automate Invoicing
Lago automatically generates and sends accurate invoices that combine all billable items for each client.
Ready to automate your workflow with Lago?
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Real Impact

Before & After

❌ Before

Manually calculating and invoicing for complex, multi-part client contracts using spreadsheets.

✅ After

Automated, accurate billing for any hybrid model, with a single source of truth for revenue.

AI Prompts

Prompts for Consultants

Prompt 01 Prompt: Draft a Project Scope Section
Act as a management consultant drafting a scope of work for a client proposal. The client, [[Client Name]], wants to improve their employee onboarding process.
Prompt 02 Client Feedback Synthesis
[Paste a collection of raw client feedback from emails, surveys, call notes, etc.] • Email 1: "The new dashboard is too confusing. I can't find the report I need." • Survey Response: "I love the new feature, but it's slow to load." • Call…
Prompt 03 Client Discovery Analysis Prompt (for Claude/GPT-4)
Act as a management consultant. I've uploaded the transcripts from three discovery calls with a new client, [[Client Name]]. The client is a [[describe industry and size]] facing challenges with [[e.g., customer churn, inefficient…
See all 22 AI prompts for Consultants →
Social Proof

Trusted by professionals

Ease of Use
6.2
Accuracy
9.4
Value
9.4
Time Saving
9.0
Connects With

Lago integrations

Payment providers Accounting systems CRMs Data warehouses Marketplaces Workflow & automation tools Auth & entitlements systems
Setup complexity: Requires Developers
Lago is an open-source, API-first billing platform designed for professional services firms with complex revenue models. It automates invoicing for hybrid structures like subscriptions, usage-based fees, and custom enterprise contracts. This gives finance and operations teams a single, transparent system for all billing data.
Comparison

Best Lago alternatives

**Lago vs. Stripe Billing**: Stripe Billing is excellent for straightforward subscription and metered billing, deeply integrated into Stripe's payment ecosystem. It's fast to set up for common use cases. Choose Stripe if your billing is relatively standard and you're already committed to its payment processing. Lago is the superior choice when billing logic becomes highly complex and non-standard. Its open-source, API-first nature allows for unparalleled flexibility to model any hybrid plan (e.g., retainers + multiple usage tiers + one-off fees), self-host for data control, and integrate with any payment provider, not just Stripe. Pick Lago for maximum control and complexity.

The decision

Is Lago worth it?

Return on investment
By automating complex invoicing that mixes retainers and usage, a firm can reclaim dozens of hours per month from manual spreadsheet work, justifying the investment after the first few billing cycles.
Built for
Finance, Operations, and Engineering leaders in professional services firms, consultancies, and agencies that manage complex, multi-part client contracts.
Effort to adopt
Requires Developers
Compliance
Lago is SOC 2 Type II compliant, ensuring data is protected with enterprise-grade security protocols.
Who It's For

Why General (Professional Services) choose this tool

🎯
Built for
Best for professional services firms needing to automate and scale complex, hybrid billing models that mix retainers, usage, and project fees.
In-Depth Overview
Professional services firms often struggle with billing clients on complex, non-standard agreements that spreadsheets and basic invoicing tools can't handle. Lago is built specifically for this complexity. Instead of manually tracking billable hours against a retainer or calculating tiered project fees, you can automate it all. The platform's core strength is its ability to create 'hybrid plans,' combining recurring subscriptions with any number of usage-based metrics. This means you can model and bill for a monthly retainer plus metered consulting hours, all in one invoice. As an open-source platform, Lago provides complete transparency and control over your billing logic and data—a critical factor for financial operations. You can self-host it to meet strict data residency or security requirements. Proof of its capability comes from its adoption by tech leaders like Mistral AI for their own complex billing needs. With SOC 2 Type II compliance, Lago provides the enterprise-grade security necessary for handling sensitive client financial data, giving your firm a scalable, auditable, and automated billing engine.

Key Use Cases

💼
Automate Complex Client Invoicing
Operations Manager, Consulting Firm
A boutique tech consultancy uses Lago to bill clients on a hybrid model: a monthly retainer plus metered hours for specialist support. Lago automatically tracks hours, combines them with the retainer, and generates a single, accurate invoice.
Reduced manual invoicing time.
✓ Pros
Handles highly complex, hybrid billing models (e.g., retainers + usage).
Open-source core offers transparency and self-hosting control.
SOC 2 Type II compliant, ensuring enterprise-grade data security.
API-first design allows deep integration with existing CRM and ERP systems.
Empowers non-technical teams to manage pricing via a visual interface.
· Cons
Requires engineering resources for initial setup and integration.
Can be overly complex for firms with simple, fixed-fee billing.
Pricing for the premium version is not public, requiring a demo.
⚡ Editorial Verdict

Lago is a powerful, developer-friendly solution for professional services firms that have outgrown simple invoicing tools. Its strength is its flexibility in handling any conceivable billing logic, from metered consulting hours to multi-product retainers. The main trade-off is its complexity; it requires engineering resources to implement and is not an out-of-the-box solution for simple billing.

Questions & Answers

Frequently asked questions

What kind of billing models can Lago handle for a consulting firm?

+
Lago is designed for complexity and can handle virtually any model, including fixed monthly retainers, pure usage-based billing (e.g., per hour, per project), tiered pricing, and hybrid models that combine recurring fees with metered usage.

Is Lago suitable for a non-technical operations team?

+
While initial setup and integration require engineering resources, Lago provides a visual interface for day-to-day management. Once configured, finance and operations teams can manage pricing, view analytics, and handle invoicing without writing code.

Can Lago be deployed on our own servers?

+
Yes. Lago is an open-source platform that offers flexible deployment options. You can deploy it on your own infrastructure (on-prem), in a private cloud (VPC), or use Lago's managed cloud service, giving you full control over data residency and security.

How does Lago ensure data security for client billing information?

+
Lago is SOC 2 Type II compliant, which means it adheres to rigorous, third-party audited standards for data security, availability, and confidentiality. It also offers features like Role-Based Access Control (RBAC) and the option to self-host for maximum data control.

Does Lago integrate with accounting software like QuickBooks or Xero?

+
Yes, Lago is designed to connect to your existing financial stack. It supports integrations with accounting systems, CRMs, ERPs, and payment providers to ensure a seamless quote-to-cash workflow.

What is the best AI billing tool for a professional services firm with complex contracts?

+
For professional services firms with complex client contracts, Lago is a leading AI-powered billing platform. Its strength lies in automating hybrid models that mix retainers, project fees, and usage-based billing. Its open-source, API-first nature and SOC 2 compliance provide the flexibility and security needed to manage sophisticated revenue streams.

Last reviewed:

Plans & Pricing

Lago pricing and plans

Prices and features are updated regularly but can change at any time — always confirm on the official website. Some links on this page are affiliate links.

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Free guide

Take it with you

Getting Started with Lago for Professional Services
  • Map Your Service Contracts to Lago's Models
  • Understand Usage Metering for Billable Hours
  • Connect Your CRM and Time-Tracking Tools
  • Automate Invoicing & Dunning
  • Leverage Revenue Analytics for Client Insights
+3 more steps inside the guide
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AI Directory

About Lago

Full Description

Lago is an open-source, API-first billing platform designed for professional services firms with complex revenue models. It automates invoicing for hybrid structures like subscriptions, usage-based fees, and custom enterprise contracts. This gives finance and operations teams a single, transparent system for all billing data.

Editorial Verdict

Lago is a powerful, developer-friendly solution for professional services firms that have outgrown simple invoicing tools. Its strength is its flexibility in handling any conceivable billing logic, from metered consulting hours to multi-product retainers. The main trade-off is its complexity; it requires engineering resources to implement and is not an out-of-the-box solution for simple billing.

Last reviewed:
Disclaimer
Zekai is an independent AI tools directory. We are not affiliated with, endorsed by, or officially connected to Lago unless clearly stated. All product names, logos, and brands are the property of their respective owners and are used for identification purposes only. The information on this page — including pricing, features, and availability — is general information, may have changed since our last review, and is not professional advice. Zekai Scores and verdicts are our editorial opinion. Some outbound links are affiliate links that may earn us a commission at no extra cost to you. Spotted outdated or incorrect information? Request a correction →
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