nixfredFLY.IOFIELD GUIDE · BY NIX UNOFFICIAL
ObjectionsReliabilityFAQGlossaryBlog digestWhat is Fly.ioArchitectureSpritesEnterpriseUnofficial. Not affiliated with Fly.io.
HOW TO WIN AND KEEP CUSTOMERS ON FLY.IO · UNOFFICIAL FIELD GUIDE · BY NIX

Firecracker VMs you can start and stop on demand.
Billed by the second while they run.
Know how to make them succeed.

An independent guide to Fly.io: the pitch, objection handling, a support playbook, honest reliability notes, head-to-head comparisons with Render, Railway, Heroku, Vercel, Cloudflare, AWS and agent-sandbox vendors, economics and cost math, whiteboards, a POC playbook, a digest of every fly.io/blog post and a quiz. Fly.io facts come from its own docs and blog and competitor facts from each vendor's public page, with a source on every claim.

Sources for this headline: application code runs in Firecracker microVMs (architecture); Machines can be stopped and are started again by Fly Proxy when a request arrives (autostop and autostart); started Machines are billed per second (billing).

Start with the pitch →ObjectionsSupport playbookReliabilityCompetitiveWhiteboardsCost calculatorPOC scripts
$2.19shared-cpu-1x 256 MB /mo
$0.02per GB egress, NA and EU
$38Managed Postgres Basic /mo
2026-11-04sources checked

WHITEBOARDS

BOARD

request path

A browser request to a Machine that is stopped

BOARD

agent sandbox

An agent with a persistent computer and checkpoints

BOARD

stateful app

Volumes, snapshots, replicas and what survives a host loss

BOARD

multi-region

Regions, replay, read replicas and the cost of going global

EXECUTE

EXECUTE

The pitch

One-liner, 30-second and 2-minute versions, discovery, value by persona

EXECUTE

Objection handling

Reliability, price, lock-in, scale and competition, each with a source

EXECUTE

Support playbook

Triage, the first five questions, common failures and the docs that fix them

EXECUTE

Reliability, honestly

Status, incidents, postmortems, what Fly has said and how to talk about it

EXECUTE

Economics

What Fly bills for, worked examples, scale-to-zero math, calculator

EXECUTE

Competitive positioning

Render, Railway, Heroku, Vercel, Cloudflare, AWS, E2B, Modal and more

EXECUTE

POC and demo scripts

Five demos, success criteria, close-out

LEARN

LEARN

What Fly.io is

30-second and 2-minute versions, who it is for, vocabulary

LEARN

The architecture

Firecracker, own hardware, proxy, WireGuard mesh, flyd, Corrosion

LEARN

Apps, Machines and volumes

Lifecycle, sizes, regions, autostop, volumes, deploy strategies

LEARN

Proxy, networking, domains, TLS

Anycast, Fly Proxy, Flycast, 6PN, IPs, certificates, WireGuard

LEARN

flyctl, Machines API, tokens

fly.toml, CLI, REST API, tokens, CI/CD, limits

LEARN

Data and integrations

Managed Postgres, Tigris, Redis, secrets, extensions, observability

LEARN

Sprites and agents

Sprites, checkpoints, MCP, skills, running agent workloads

LEARN

Orgs, support, enterprise

Organizations, SSO, support plans, compliance, SLA

REFERENCE

REFERENCE

FAQ quickfire

One-line answers with sources

REFERENCE

Glossary

Terms to use correctly

REFERENCE

Sources

Every Fly.io and competitor URL, date checked

REFERENCE

Fly.io blog digest

Every fly.io/blog post with the one fact worth repeating and when to use it with a customer

REFERENCE

Quiz and flashcards

Check yourself before the call

MCP SERVER

Use this guide in your agent

Read-only tools over Fly.io docs and this guide

MODEL CONTEXT PROTOCOL

Put Fly.io's docs in your own agent.

A read-only MCP server that fetches Fly.io's docs live from llms.txt, plus this guide's pages.

claude mcp add --transport http flyio-field-guide https://flyio.nixfred.com/mcp

All clients and tools →

Index

This is an unofficial field guide to Fly.io, the platform that runs apps and agent sandboxes in Firecracker microVMs on its own servers (https://fly.io/docs/reference/architecture/). Start with what Fly.io is, then Machines and apps, networking and the edge, agents and Sprites, economics, competitive positioning, the POC playbook, the quiz and the blog digest.

Fly.io facts come first from its documentation (https://fly.io/docs/machines/overview/), its blog (https://fly.io/blog/) and its live product pages (https://fly.io/sprites, https://fly.io/support). Competitor facts come from each vendor’s own public pages. Everything was checked 2026-11-04 and is listed on Sources. Where a claim could not be settled, the page marks it with a [verify] badge. This guide is not written, reviewed or endorsed by Fly.io.