獨家架構與決策對照表
深度解構 Amplitude 與 PostHog 在資料架構、運維開銷與授權風險上的核心指標差異。
For modern engineering and finance teams, navigating Amplitude’s pricing model can lead to significant sticker shock due to its steep escalations as monthly tracked users (MTUs) scale. While Amplitude provides exceptional product analytics, many organizations seek a self-hosted, open-source alternative like PostHog to reclaim data ownership and eliminate unpredictable SaaS overage fees.
Amplitude Official Pricing Plans
| Plan | Price (Billed Monthly) | Price (Billed Annually) | MTU Limit | Key Highlights |
|---|---|---|---|---|
| Free | $0 | $0 | Up to 50,000 MTUs | Core analytics charts and basic data planning. |
| Plus | $61 / month | $49 / month | Up to 100,000 MTUs | Behavioral cohorts, retention analysis, custom dashboards, standard integrations. |
| Growth | Custom Quote | Custom Quote | Custom (Scales past 100k) | Advanced behavioral analytics, predictive cohorts, real-time user paths, data governance tools. |
The Hidden Costs of Amplitude
While the entry-level pricing seems accessible, scaling with Amplitude introduces several indirect and hidden expenses:
- Overage Fees: Overage fees apply when exceeding MTU limits (such as the 100,000 MTU threshold on the Plus plan).
- Modular Feature Add-Ons: Amplitude Experiment, Session Replay, and full CDP features are billed separately as add-ons.
Total Cost of Ownership (TCO) Analysis: PostHog Self-Hosted
To bypass these fees, many engineering leads look to PostHog, a highly active open-source alternative (35,168 GitHub stars, MIT License, 50,000,000+ Docker pulls). However, self-hosting an analytics suite on your own infrastructure shifts the cost profile from software licenses to hosting resources and engineering overhead.
1. Hosting & Server Resource Estimation
- Small Scale (<100k MTUs): Can easily run on a single virtual machine (e.g., AWS EC2
t3.largeor DigitalOcean Droplet) with 4 vCPUs, 8–16 GB RAM, and SSD block storage.- Estimated Cost: $50 – $100 / month
- Medium Scale (100k – 1M MTUs): Requires a split setup with a dedicated ClickHouse database instance, separate web/ingestion servers, and Redis for caching. Recommended: 16 vCPUs, 32–64 GB RAM.
- Estimated Cost: $300 – $800 / month
- Large Scale (1M – 10M+ MTUs): Requires a highly available, multi-node ClickHouse cluster, managed Kafka for ingestion queuing, load balancers, and substantial high-speed SSD storage.
- Estimated Cost: $1,500 – $4,000+ / month
2. Maintenance & Engineering Support Estimation
Self-hosting means your engineering team acts as the DevOps provider.
- Small Teams: ~2–4 hours per month for basic OS updates, database backups, and certificate renewals. (Estimated internal cost: $200 – $400 / month).
- Medium Teams: ~10–20 hours per month handling data migrations, schema optimizations, and performance tuning as volume scales. (Estimated internal cost: $1,000 – $2,000 / month).
- Large Teams: Dedicated engineering attention (approximately 0.25 to 0.5 FTE) to manage scaling pipelines, troubleshoot Kafka lags, and maintain infrastructure health. (Estimated internal cost: $3,000 – $6,000+ / month).
Comparative TCO Table (SaaS Fees vs. Self-Hosted Infrastructure)
| Scale (Monthly Tracked Users) | Amplitude SaaS Monthly Cost | PostHog Infrastructure Cost | PostHog DevOps Overhead | PostHog Total Monthly TCO |
|---|---|---|---|---|
| 50,000 MTUs | $0 | $50 | $200 | $250 |
| 100,000 MTUs | $49 – $61 | $100 | $200 | $300 |
| 500,000 MTUs | ~$1,200 – $2,500 (Growth) | $400 | $1,200 | $1,600 |
| 5,000,000+ MTUs | ~$8,000 – $15,000+ (Enterprise) | $2,500 | $4,000 | $6,500 |
Scenario Analysis: Cost by Team Size
Scenario A: The 5-User Early-Stage Startup
- The Setup: A small team managing under 100,000 MTUs.
- Amplitude Cost: $49 – $61 / month.
- PostHog Self-Hosted Cost: ~$300 / month (factoring in the opportunity cost of developer time).
- Verdict: Amplitude wins on pure cost. At this scale, the developer time required to manage self-hosted infrastructure outweighs Amplitude’s heavily subsidized low-tier SaaS pricing.
Scenario B: The 20-User Scale-Up
- The Setup: A growing team managing 500,000 MTUs.
- Amplitude Cost: Custom Growth Contract (Estimated $1,500 – $2,500/mo).
- PostHog Self-Hosted Cost: ~$1,600 / month ($400 hosting + $1,200 maintenance time).
- Verdict: PostHog emerges as the strategic winner. While the dollar amounts are comparable, PostHog gives the engineering team complete data ownership (Data Ownership Score: 10 vs. Amplitude’s 2), and allows unlimited user seats without seat license inflation.
Scenario C: The 100-User Enterprise
- The Setup: An enterprise with multiple product lines and 10,000,000+ MTUs.
- Amplitude Cost: $10,000+ / month (subject to strict vendor lock-in).
- PostHog Self-Hosted Cost: ~$7,000 / month ($3,000 hosting + $4,000 dedicated SRE resource).
- Verdict: PostHog is significantly cheaper and more secure. At enterprise scale, Amplitude’s pricing escalates rapidly. Hosting PostHog internally mitigates data export/egress fees and satisfies strict security, compliance, and GDPR/HIPAA requirements.
When Does Paying for Amplitude Actually Save Money?
Despite the cost-saving potential of open source, investing in Amplitude SaaS is the financially wiser choice under the following conditions:
- Strict Engineering Constraints: If your development team is already at maximum capacity building core product features, distracting them with database maintenance, ClickHouse clustering, and telemetry pipeline management is an expensive misuse of engineering resources.
- Advanced Out-of-the-Box Analytics Needs: Amplitude’s proprietary predictive analytics, advanced machine learning cohorts, and built-in data governance UI are incredibly mature. If your product managers and growth marketers rely heavily on automated pathfinder analysis and predictive churn modeling, replicating these in PostHog would require significant custom analytics builds.
- Low In-House Infrastructure Expertise: ClickHouse and Kafka (which back high-scale PostHog setups) require specialized backend expertise to run efficiently. If your team does not have strong DevOps or data-engineering skills, self-hosting risks frequent data loss, pipeline downtime, and inaccurate tracking dashboards.
Final Purchasing Recommendation
- Choose Amplitude if: You have a non-technical marketing/product team, no dedicated DevOps resources, and you are scaling under 100,000 MTUs. Paying Amplitude’s subscription fee allows you to run on a zero-maintenance SaaS architecture (DevOps Overhead Score: 1) and utilize best-in-class UI tools immediately.
- Choose PostHog (Self-Hosted) if: You are an engineering-driven organization that prioritizes strict data privacy, wants to avoid vendor lock-in, and already has the infrastructure capability to manage databases. Hosting your own PostHog instance will drastically lower your long-term marginal costs, allow unlimited seat expansion, and keep 100% of your user telemetry data securely within your own cloud boundary.
Cost and pricing analysis verified as of 2026-06-26. Self-hosting costs are estimates based on standard cloud providers.