Belkis Castillo Customer Success · Barcelona

Customer Success Manager · Building with AI

Eight years turning enterprise SaaS customers into long-term partners.

Belkis Castillo
$3.8M ARR managed at MongoDB
91%+ Gross retention, strategic portfolio
110% Of renewal target at Tableau

Four stories behind the numbers.

Click any story to read the full version.

When I joined as the first dedicated CSM for the Middle East region, the company had customers there but no playbook for serving them. I built that playbook end to end: segmentation, onboarding cadence, QBR structure, escalation paths, stakeholder mapping templates.

Portfolio engagement on the region grew from 36 percent in August 2021 to 55 percent two months later, and reached 73 percent within a year. That meant moving the customer base from infrequent ad-hoc check-ins to monthly strategic conversations across the entire portfolio.

The accounts I managed included a major regional telecom operator, a regional grocery delivery platform, a major media company, a regional transport authority, and several financial institutions. Each market had its own cultural and operational rhythm, and the playbook had to flex for that.

What I take from it: the difference between a region that exists on a map and a region that exists as a real CS practice is somebody willing to build the unglamorous infrastructure before the wins show up.

I was named the first internal coordinator of EMEA product certifications. The role started simple: track who was completing the five mandatory technical certifications that helped CSMs have sharper conversations with customers.

What happened next was unexpected. Once completion rates were visible, CSMs started volunteering as proctors. Others designed new certifications. Managers began competing on team completion rates. The mechanic shifted from compliance to engagement.

Twelve months later, completion rates told the story:

Atlas: 98 to 100 percent. Charts: 91 to 98 percent. Compass: 83 to 89 percent. Search: 74 to 81 percent.

The pattern I learned: making something visible is often a stronger intervention than adding incentives on top. People show up when they can see what good looks like.

The hackathon was the final step of a six-month technical training arc with a global security services company. Across that period I orchestrated four functions to deliver it.

Solutions Architecture covered technical readiness. Partners arranged sponsorship, catering, prizes, and partner-side technical support. Marketing handled communications and participant follow-up. The customer's own teams managed room logistics, attendance, and a session led by them showcasing their use cases.

The day produced two strategic workloads I had not previously seen: an internal-compliance repository and a billing operations platform. It also opened a second cadence call with the customer's Architecture Operations team, breaking a previously single-threaded relationship. They went on to give us direct access to their team leads.

Hackathons sound like marketing. Run well, they are a way to turn passive customers into champions and surface workloads that would never come up in a standard QBR.

Early in my Middle East tenure I inherited a major regional telecom operator on a five-year on-premise contract. When I took the account, only one internal stakeholder had real context on it. The customer was running their workloads entirely on legacy infrastructure, their cloud entitlements sat unused, and a significant portion of the Professional Services hours in their contract had never been consumed.

I partnered with a Professional Services consultant to map the stakeholder landscape inside the customer and inventory their active projects on the legacy stack. From there I built a two-year churn risk assessment and flagged it internally.

The diagnosis was the easy part. The hard part was getting buy-in. Several people felt that flagging risk two years out was premature. I persisted, documented everything, mapped the customer's internal decision-makers, and built a mitigation plan around surfacing the unused entitlements back to them.

When the account was reassigned, I handed over a full playbook: contacts, risk map, PS hours roadmap, and the relationship groundwork. The CSM who took over executed the plan. The renewal closed successfully.

What I take from this: churn risk in legacy accounts usually is not mysterious. It is what the account team has been too close to see. It takes someone willing to name it early to save it.

Took sole ownership voluntarily of the certification program and brought structure and focus to ICs, moderators, and managers.

Written performance review

Belkis presenting at a Tableau workshop
Presenting at a Tableau Blueprint workshop
Belkis with I love data sign
The data days, in case there was any doubt

What I'm building.

I learn AI by building things that serve a real use case. Here is what is currently in my workflow.

Recently completed

Domina la IA

An advanced AI training program with Ernesto Fuenmayor.

Certified by Universidad Central de Venezuela

Personal AI assistant

I built a custom AI assistant that runs my calendar, structures my projects, and acts as a constant project COO. It uses Claude with a system prompt I refine weekly based on what is working and what is not.

CS workflow exploration

Where AI fits inside customer success: account brief generation, transcript synthesis, draft QBR narratives from telemetry. Less interested in opinions about AI in CS, more interested in shipping the small workflows that compound.

Custom chatbots

I build Claude-powered chatbots for personal projects in production. The interesting work is iterating on the system prompt after watching real conversations, not building the first version.

A point of view

The CSMs who will matter most over the next few years are the ones hands-on with these tools. That is where my own time is going.

Say hello.