GravityHash
Engineering studio · Silicon Valley

Engineering partner
for the parts of your product
that can't fail.

GravityHash is an engineering studio. We help founders and product teams build and run the systems their business actually depends on: billing, auth, real-time data, applied AI. We stay until they're solid.

Start a project See what we're building
Production uptime
99.99%
Time to first deploy
≤ 4 wks
Senior engineers
100%
Events shipped / day
40M+
Trusted across
  • Fintech
  • SaaS
  • AI & ML
  • Climate Tech
  • Healthcare
  • Developer Tools
  • E-commerce
  • Marketplaces
  • EdTech
  • Logistics
  • Cybersecurity
  • Mobility
  • Productivity
  • Media
  • Real Estate

An engineering studio, not an agency.

We don't sell hours. We sell opinions, architecture decisions, and code that survives the next two years of your roadmap. We partner on the product, not just the spec, and the engineers in the kickoff are the same ones in the commit log.

Products

Software we build for ourselves.

Alongside client work, we ship products that solve problems our partners hit again and again. Each is a real bet, built, operated, and supported by the same team you'd hire for an engagement.

● Live v0.42 · public beta relayon.io

Relay

The webhook & event-relay platform for B2B SaaS.

Relay handles the unsexy half of every modern SaaS: outbound webhooks, inbound event ingestion, retries, signing, replay, observability, and per-customer rate limits. One reliable layer between your services and your customers' integrations.

Reliable delivery

Sub-second fan-out at 40M+ events / day with exactly-once semantics and full replay.

Secure by default

HMAC signing, automatic key rotation, and per-tenant signing keys out of the box.

Drop-in SDKs

Idiomatic clients for Node, Python, Go, and Ruby. Five lines from install to first event.

Audit & observability

Full delivery log, OpenTelemetry traces, and Prometheus metrics. Wired in, not bolted on.

Visit relayon.io Request access
● Live public beta

Sphearo

A modern CRM for product-led teams.

Sphearo treats your product data as a first-class source of truth: usage signals, billing events, and support touchpoints flow in alongside the pipeline, so revenue and customer-success teams act on what's actually happening, not what's logged a week late.

  • Pipeline
  • Usage signals
  • Workflows
In development internal · 2026

Singularity

An evaluation harness for production LLM agents.

Build, version, and grade agent behaviours against real production traces. Singularity gives engineering teams a regression-test layer for prompts, tools, and policies, so model upgrades don't ship surprises.

  • Trace replay
  • Eval suites
  • Diffing
In development internal · 2026

Orbit

Usage-based billing infrastructure.

A drop-in metering and invoicing engine for AI-era pricing (token-based, seat-based, hybrid) with sub-cent accuracy, idempotent writes, and Stripe + bank rails out of the box.

  • Metering
  • Idempotent ledger
  • Stripe + ACH
Services

Six practices, one engineering bar.

We engage either as your full delivery team or alongside your engineers. No outsourced bench, no junior hand-offs. Every line of code is written by senior engineers who care about what they ship.

Product engineering

From zero to public launch. Web and mobile product surfaces built with React, Next.js, React Native, Node, and Postgres, plus the design taste to make them feel inevitable.

  • Next.js · Remix
  • React Native
  • Tailwind · Radix

Applied AI

LLM agents, RAG pipelines, evaluation harnesses, and integrations with Claude, GPT-class, and open models. We've taken AI features from prototype to production with cost and latency budgets that hold.

  • Claude · OpenAI
  • RAG & agents
  • Eval pipelines

Platform engineering

Multi-tenant platforms, real-time systems, event-driven architectures, and the boring-but-critical glue that keeps revenue flowing: billing, auth, audit logs, and webhooks.

  • Postgres · Redis
  • Kafka · NATS
  • Multi-tenant SaaS

Data & analytics

End-to-end data platforms: ingestion, warehousing, dbt-driven transformations, semantic layers, and product analytics that survive scale and make decisions sharper.

  • BigQuery · Snowflake
  • dbt · Airbyte
  • Reverse ETL

DevOps & cloud

Infrastructure as code on AWS, GCP, and Fly.io. Cost-aware architecture, reproducible environments, observability, and the kind of CI/CD pipelines your team actually trusts.

  • Terraform · Pulumi
  • Kubernetes · Fly
  • OpenTelemetry

Fractional CTO

Architecture review, hiring loops, technical due diligence, cost & speed audits. We sit beside your team for as long as you need us. Not a sprint longer.

  • DD for VCs
  • Tech hiring
  • Architecture review
Why GravityHash

Four reasons teams pick us, and stay.

  1. 01

    Senior-only delivery

    Senior-only staffing on every engagement. No junior bench, no surprise reassignments, no learning on your dime.

  2. 02

    You own what we build

    Code, infra, cloud accounts, documentation. Yours from day one. When you're ready to take it in-house, we hand it off and walk away.

  3. 03

    Production every sprint

    You see the work every Friday. Things go live every two weeks. You always know what's shipped, what's stuck, and what we're billing.

  4. 04

    We tell you when not to hire us

    If a tool you can buy off the shelf will solve the problem, we'll point you at it. We'd rather you trust us next time than bill you this time.

Process

How an engagement runs.

We use the same playbook on every project, refined over a decade of shipping software. It's deliberately boring. Boring ships, and ships on time.

  1. 01

    Discovery

    We meet your team, read the codebase, and write a sharp project brief: scope, risks, milestones, and a fixed-fee proposal.

    ~ 1 week · fixed fee
  2. 02

    Architecture

    A clear technical plan: data model, service boundaries, integrations, and the smallest credible v1. Reviewed and signed off before code.

    ~ 1–2 weeks
  3. 03

    Build

    Weekly demos, fortnightly retros, transparent invoicing. You see progress every Friday and ship to production every sprint.

    2–6 months
  4. 04

    Operate

    Optional ongoing support: on-call, performance tuning, scale-out, and an explicit hand-off when your in-house team is ready to own it.

    Optional
Selected work

Recent gravity wells.

A small set of representative engagements. Names redacted under NDA where required.

Platform · 2026

Webhook delivery for a Series-B SaaS

Replaced a fragile in-house webhook system with a self-hosted Relay deployment. Cut p99 delivery latency from 4.1s to 180ms; eliminated 90% of customer-reported integration failures in the first month.

  • 23×faster delivery
  • 40Mevents / day
  • 0incidents in q1
Applied AI · 2025

Agentic incident operations

Built an LLM agent suite that triages PagerDuty incidents, drafts post-mortems from logs and chat history, and opens reproducer PRs for routine regressions. Now handles 60% of overnight pages without human escalation.

  • 60%auto-triaged
  • −45%MTTR
  • 3FTEs freed
Fintech · 2025

Ledger-grade usage billing

Designed an event-sourced billing engine for a usage-priced AI product: sub-cent accuracy, idempotent retries, and Stripe + ACH rails. Survived a 12× usage spike in week one without ledger drift.

  • 12×peak surge
  • $0ledger drift
  • 6 wksto launch
About

A small team.
A high gravitational pull.

GravityHash is a tight team of engineers, designers, and operators who've built and scaled software at startups and at public companies. We pick a handful of partners each year and engage like co-founders. Opinionated, accountable, and fully on the hook for the outcome, not just the output.

  • Senior-only delivery. The engineer in your standup is the engineer writing the code.
  • You own everything. Code, infra, accounts, documentation. Zero lock-in, ever.
  • Weekly demos, monthly retros, transparent invoices. You always know what's shipped, what's blocked, and what's billable.
  • Bias to ship, bias to delete. The best line of code is the one we didn't write.
Stack

Tools we reach for first.

Language-agnostic but opinionated. These are the tools we've shipped to production hundreds of times, and the ones we'll recommend unless there's a sharp reason not to.

  • TypeScript
  • Node.js
  • Next.js
  • React
  • React Native
  • Python
  • Go
  • PostgreSQL
  • Redis
  • Kafka
  • AWS
  • GCP
  • Fly.io
  • Terraform
  • Kubernetes
  • Claude
  • OpenAI
  • dbt
  • BigQuery
  • Snowflake
FAQ

Common questions.

If yours isn't here, write to us. We usually reply the same day.

What size of engagement do you take on?

Most engagements run between 6 weeks and 9 months. We've done short architecture reviews and we've embedded for over a year. The sweet spot is a focused 2–4 month build with one or two senior engineers and a tech lead.

Do you work fixed-fee or time & materials?

Both. Discovery is always fixed-fee. After that, the build phase is usually time & materials with a hard ceiling and weekly burn reports. For well-defined scopes, we'll quote fixed-fee.

Where is the team based?

Silicon Valley, with engineers distributed across the US, UK, and EU. We work in your team's primary timezone and cover US Pacific, Eastern, and European hours by default.

Do you sign NDAs and assignment-of-IP?

Yes, standard practice on every engagement. Your code, your IP, full stop.

Can you work alongside our existing engineering team?

Absolutely. That's most of what we do. We code-review, pair, and follow your conventions. We're additive, not adversarial.

What does an engagement cost?

Discovery is typically $5–10K. Build engagements range from $25K (a focused 4-week sprint) to $250K+ (a multi-quarter platform build). We'll give you a clean number after the discovery week.

Have a hard problem?

We like hard problems.

One business day to first reply. Thirty minutes for a discovery call. No commitment.

Start the conversation hello@gravityhash.com
Let's talk

Tell us what you're building.

We reply within one business day. If you'd rather email directly, reach us at hello@gravityhash.com.

Hours
Mon–Fri · 09:00–19:00 PT
Discovery call
30 min, no commitment
Response time
≤ 1 business day

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