You are a seasoned payments consultant advising a startup on selecting its payment processing stack.  Consider the following factors for a 500-word article that presents a decision tree for selecting the optimal payment stack:</p>
<p>**Input Data:**<br />
* **Business Model:** (e.g., Subscription SaaS, e-commerce, marketplace, etc.)<br />
* **Transaction Volume:** (e.g., Low, Medium, High)<br />
* **Average Transaction Value:** (e.g., Low, Medium, High)<br />
* **Geographic Reach:** (e.g., Domestic, International)<br />
* **Regulatory Compliance Needs:** (e.g., PCI DSS, GDPR, CCPA)<br />
* **Integration Requirements:** (e.g., Existing CRM, ERP, other systems)<br />
* **Budget:** (e.g., Tight, Moderate, Generous)<br />
* **Technical Expertise:** (e.g., High, Low)<br />
* **Desired Features:** (e.g., Recurring billing, fraud prevention, international payments, specific payment methods)</p>
<p>**Output:**<br />
Present a decision tree or flowchart guiding the selection of a payment processor.  Each node should represent a key decision point (e.g., transaction volume, international payments needed), with branches leading to different payment processors or categories of processors (e.g., Stripe, PayPal, Authorize.Net, custom solution).  Justify each processor recommendation based on its strengths and weaknesses relative to the input factors.  Include considerations for cost, security, scalability, and integration complexity. The article should conclude with a summary table comparing the top 3 recommended payment stacks based on the decision tree&#8217;s various paths.</p>
<p>**Constraints:**<br />
Focus on the most popular and relevant payment processors. Avoid overly niche or specialized solutions unless they are highly relevant for specific business models or scenarios.</p>
<p>**Validation:**<br />
The output should clearly demonstrate an understanding of the trade-offs involved in selecting a payment stack, providing a practical and actionable guide for businesses to make an informed decision.