---
title: "API integration services by senior engineers"
description: "Senior engineers connect your app to Stripe, HubSpot, Salesforce, Twilio, Slack and custom APIs, with syncs that hold up. Single integrations start at $1,000."
url: https://zeroic.in/api-integration-services
---

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# API integrations that keep working after launch.

[Talk to an integration engineer](https://zeroic.in/book) [See the work](https://zeroic.in/work)

**Starting at**

$1,000

**Retainers from**

$4,000/mo

**Products shipped**

40+

## Where most teams are

Connecting two systems takes a day. Keeping them in sync when one goes down, hits a rate limit or changes its data is the real work. Our engineers built 40+ data connectors for an analytics app used by 1.5M+ people, and the payment, banking and scheduling integrations behind several products on this site.

Syncs fail and nobody notices → Failures logged, retried and flagged

Data drifts between two systems → One source of truth for each record

Every new integration is a one-off → Integrations built on one clean pattern

Rate limits break things at scale → Built around each API's limits

## Integrations we build

### Payments

Stripe subscriptions, Connect payouts and the webhooks behind them, plus PayPal or Razorpay where your customers need them, so billing always matches what your app shows.

### CRM and sales

HubSpot and Salesforce synced both ways with your app. We decide which system owns each field and plan around API limits, so neither side quietly overwrites the other.

### Messaging and email

Email through Resend, SendGrid or Postmark, SMS and WhatsApp through Twilio, and Slack alerts, with delivery tracked, failed sends retried and opt-outs respected.

### Sign-in and OAuth

Google, Microsoft or GitHub sign-in, Clerk or Auth0, and OAuth 2.0 so your app can act on a user's own accounts, with tokens stored safely and refreshed before they expire.

### Calendars and scheduling

Google Calendar, Outlook and Calendly, so bookings, reminders and availability show up where your users already plan their day, without double bookings or missed changes.

### Banking and accounting

Plaid for bank accounts and transactions, QuickBooks or Xero for invoices and books, so financial data flows into your product without anyone copying it across by hand.

### Data and AI models

OpenAI and Claude APIs, plus BigQuery, Snowflake and Postgres, connected so your AI features and reports read live data, with costs and rate limits watched from day one.

### Files and e-signatures

S3 and Google Drive for uploads and shared files, DocuSign for contracts, so documents land in the right place, with the right access, and signed copies sync back on their own.

### Maps and location

Google Maps or Mapbox for search by area, routes, distance and live tracking, with address lookup that catches typos and API usage kept within budget as traffic grows.

### Video and calls

Zoom, Daily or Twilio Video for calls inside your product, with rooms created per booking, links sent on time and recordings stored where your users can find them.

### Analytics and tracking

PostHog, Segment or Google Analytics wired to the events that matter, named the same everywhere, so you can see where users drop off and trust the numbers you report.

### Your own APIs

Private APIs your team wrote, and new ones we design for partners to build on: documented, versioned and safe to depend on, so the next integration is quicker than the last.

## How it works

1. 01

### Pick a tier

Part-time, dedicated or embedded, from $4,000 a month. Tiers differ in hours and in how closely we work with your team.
2. 02

### Map the systems

A senior engineer maps which system owns which data, how often it changes and where it can fail, before writing any sync code.
3. 03

### Ship every week

Integrations, syncs and fixes. The engineer doing the work is the one on your calls. Change tier or stop any month.

Starting at $1,000

One integration, one fixed price, agreed after a short call. Single integrations start at $1,000. Need ongoing work? Part-time retainers from $4,000/month, month to month. Payments are the main job? See [payment gateway integration](https://zeroic.in/payment-gateway-integration).

[Talk to an integration engineer](https://zeroic.in/book)

Jatin Mukheja rebuilt our onboarding, shipped our Zapier integrations, and wrote integrated plugins for our proprietary tools - all in record time. He ships better than we spec. This team is literally an extension of mine.

Austin Gegg

Austin Gegg CEO @ Knimble

## Work we've shipped

AI · Analytics

### [Better Analyst (formerly FormulaBot)](https://zeroic.in/formulabot)

An analytics app used by 1.5M+ people. We built its 40+ data connectors, BigQuery to Postgres.

AI · Prompt tools

### [Prompt Genie](https://zeroic.in/prompt-genie)

A shared prompt library. Stripe plans, upgrades and proration, kept in step through webhooks.

Consumer · FinTech

### [Finance Girlie](https://zeroic.in/finance-girlie)

A personal finance platform for Muslim women. We built Plaid bank linking and transaction sync.

Further reading

- [English-to-SQL at a million users: what breaks, in order](https://zeroic.in/blog/english-to-sql-at-1m-users)

## How we can help

Four ways to work with us - pick what fits, switch when it doesn’t.

From $1,000 · 1-2 weeks

### [Audits](https://zeroic.in/services/ai-audit)

Find what's broken - or whether AI is worth it - before you build.

Learn more

From $12,000 · 5-6 weeks

### [MVP Sprint](https://zeroic.in/services/mvp-development)

Zero to production in 5-6 weeks. A real product, not a prototype.

Learn more

From $4,000/mo · Recurring

### [Retainer](https://zeroic.in/services/senior-developers)

A senior engineer embedded on your team, month to month.

Learn more

From $6,000 · 2-4 weeks

### [Code Rescue](https://zeroic.in/services/code-rescue)

Vibe-coded app breaking under real users? We rebuild it to hold.

Learn more

[Compare all services](https://zeroic.in/services)

FAQ

## Frequently asked questions

How much do API integrations cost?

A single integration, such as Stripe checkout or transactional email, has one fixed price, agreed after a short call. Prices start at $1,000. Ongoing integration work runs on a retainer from $4,000 a month, month to month.

Which APIs do you work with?

Named APIs such as Stripe, HubSpot, Salesforce, Twilio, Slack and Plaid, data sources such as BigQuery, Snowflake and Postgres, and private APIs your own team wrote. REST, GraphQL, webhooks or older SOAP: if we can read its docs or its code, we can integrate it.

What happens when an integration fails?

We build every integration so a failure is logged, retried where that is safe and flagged to a person where it is not. What else is possible depends on the API: some let you replay missed events, some do not. We tell you which before we build.

Can you build an API for other products to use?

Yes. We built the API that let other products embed an AI quiz generator. We design APIs to be documented, versioned and safe to depend on.

Do we own everything you build?

Yes, 100%. You own the code, API keys, docs and credentials.

## Hear from us within 24 hours.

**Prashant and Khushi** Partners @ Zeroic

Need two systems to talk? Tell us what you want connected and what's breaking today. We'll suggest the tier that fits.

Rather talk it through? [Book a 30-minute call](https://zeroic.in/book)

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