Tancrède Simonin.
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Freelance fullstack engineer

Business impact.Technical rigor.Compliance by design.

I design and build secure, robust, compliant financial APIs and systems, for demanding banks and fintechs.

They trusted me

Tancrède
Transparency

An honest opinion, not the convenient one.

Self-driven

I adapt, take ownership, and deliver.

Communication

I transfer as much as I deliver: clean docs, clear words.

How I work.

Business first
Business need and client impact first. I build products from idea to production. Not just code.
1
Business problem
2
Product decision
3
Delivery
Technical rigor
I learn fast and go deep: from application code (TypeScript, NestJS, DDD) to infrastructure (DevOps, Terraform) when needed.
api-gateway.ts
@Controller('/v1/accounts')
export class AccountsController {
  @Get(':iban/transactions')
  @UseGuards(AuthGuard, ConsentGuard)
  async getTransactions(
    @Param('iban') iban: string,
  ) {
    return this.service.list(iban);
  }
}
Security & compliance by design
DSP2, RTS, GDPR and security built in from the start.
Security & compliance
DSP2 · Strong Customer Auth (SCA)
RTS · Secure Communication
GDPR · Data Minimization
OAuth2 / OIDC · Token Security
API Rate Limiting & Throttling
Penetration Test Report
Right now

openfinanceguide.com

Open banking: "nobody gets it." And yet all of fintech runs on it. I'm building an open reference to make it simple: STET handbook, glossary. A passion project, maintained continuously.

  • Multi-version STET handbook
  • Open banking glossary
Explore openfinanceguide.com
openfinanceguide.com

They worked with me.

“

"Tancrède supported us really well throughout the development of a backend for our application. He understood our business constraints and adapted, delivering a solution that fit our needs. He has a real gift for making his technical expertise feel simple and easy to grasp. I highly recommend him."

Valentin Mercier

Founder@Tastyn ·

Valentin Mercier
“

"What sets Tancrède apart is his team spirit. Open and communicative, he makes it easy to share ideas and helps create a positive working atmosphere. He is one of those people who put "we" before "I", and that makes all the difference. His backend expertise helped us understand the challenges we could face while building a SaaS as complex as Roger."

Thomas Checkaiban

Advisor & Coach ·

Thomas Checkaiban
“

"Tancrède carried out his assignment with seriousness and efficiency. He built an API and an admin dashboard for us to manage transactions with connected refrigerators. He developed and deployed the app successfully. It runs very well. I highly recommend him."

Richard Beausse

Key Account Manager ·

Richard Beausse
“

"Being Tancrède's co-founder was probably the most rewarding experience I've had. Beyond his listening skills and his calm under pressure, what impressed me most was how fast he learns across every field, driven by boundless curiosity."

Paul Weill

Founder ·

Paul Weill
See all reviews
Contact

Get in touch

A project, a question, or just want to chat? Drop me a line.

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