About Backfire

Backfire is Tsukaeru’s cloud file storage, sync, and sharing platform — built in-house so Tsukaeru and its resellers own every layer of the stack, from the edge proxy down to the encrypted bytes on disk.

It’s designed for the full customer base: billions of files, tens of thousands of users, and petabytes of aggregate storage across all companies. Data stays on Tsukaeru hardware, in Japan, under Tsukaeru’s operational control.

Why Backfire

Three principles shaped the decision to build it in-house rather than resell someone else’s platform.

Control plane in Japan. Incident response, feature velocity, and compliance reviews all move at the speed of the team closest to the customer. Tsukaeru wanted full operational ownership — code, data, and uptime decisions — on home soil.
Japanese market fit. White-label branding, reseller hierarchies, and partner onboarding are first-class concerns, not bolt-ons. Backfire’s reseller model, per-reseller packages, and custom-domain support are built around how Tsukaeru and its partners actually sell.
Data sovereignty. Every byte of customer data — file content, metadata, audit logs, and encryption keys — is stored on Tsukaeru infrastructure in Japan. No foreign cloud provider sits in the trust boundary.

Architecture at a glance

Every file is chunked, deduplicated, compressed, and encrypted before it lands on disk. Encryption keys live in a separate key-management service (OpenBao Transit) — even the application servers never see raw key material. The database enforces per-company isolation at the row level, so a query that forgets to filter by company simply returns nothing.

Capabilities

Multi-company, isolated

Every company’s files, metadata, and audit trail live in a strictly isolated slice of the platform. Resellers manage their companies; a reseller admin never sees file contents unless the company explicitly grants a membership.

Desktop sync

Native Windows, macOS, and Linux client. Bidirectional sync with conflict handling, selective sync, and an offline queue that replays when the connection returns.

Web portal

Modern browser experience for file browsing, sharing, version history, and trash recovery. Works on desktop and tablet.

Sharing

Share with colleagues inside a company, or externally via public links with optional passwords, expiry dates, and reseller-admin approval before a link goes live.

Reseller white-label

Per-reseller branding — custom domain, logo, colours, login-page copy, email templates. Tsukaeru holds the master switch; resellers self-serve everything else.

Audit + ransomware detection

Every file operation, auth event, and admin action is recorded. Anomalous patterns (mass deletes, mass encryptions) trigger alerts so you catch ransomware activity while a recovery window still exists.

Security and compliance

Encryption at rest. Every file chunk is encrypted with AES-256-GCM before it touches disk. Keys are managed by OpenBao Transit, segmented per company; the application never holds raw key material.
Encryption in transit. HTTPS everywhere, TLS terminated at the edge. Reseller custom domains get on-demand Let’s Encrypt certificates without manual provisioning.
Per-company isolation enforced by the database. PostgreSQL Row-Level Security policies mean that even a bug in application code cannot leak one company’s data to another.
Audit trail. Every mutation is logged with actor, resource, timestamp, and outcome. 90 days of sync-grade event history; longer-term audit retention configurable per deployment.
Ransomware recovery. The platform keeps a configurable file-version history, and the underlying distributed filesystem provides a second layer of trash retention — even if an attacker erases a file, it’s still recoverable for a window.

For a technical deep-dive — threat model, encryption envelope format, RLS policy design — engineering teams evaluating Backfire can request the internal documentation through their Tsukaeru account manager.

Where we are, where we’re going

Shipped. The foundational contexts are live: blob storage with content-defined chunking, identity and reseller hierarchy, chunked upload/download, file catalog with version history, and the web portal. The API has been migrated to ConnectRPC so scripts and browsers alike can talk to it.

In progress. The desktop sync client reached feature-complete functionality (watcher, offline queue, three-tree reconciliation, conflict handling, ConnectRPC client). The tray UI and virtual-drive experience are the next client-side deliverables.

Coming up. Scaling and hardening for production load, staging environment with full observability, high-availability rollout across the Tsukaeru fleet, and on-demand file hydration (virtual drive) so devices can show an entire workspace without downloading every byte.

Who built it

Backfire is built by Tsukaeru’s platform engineering team in Rust (backend, desktop client) and Svelte (web portal), running on Tsukaeru’s own Virtuozzo Hybrid Infrastructure — the same cloud Tsukaeru already operates for its customers. PostgreSQL handles the catalog; the encrypted storage rides on a distributed filesystem tuned for billions-of-files scale.

The codebase is modular by design: each bounded context (storage, identity, sharing, sync, and the rest) is a separate Rust module with enforced boundaries, deployable as one binary today and splittable later if scale demands.

Get started

User Guide Sign in, upload files, share with colleagues, and set up the desktop sync client.

Talk to Tsukaeru For pricing, deployment in your region, or a technical deep-dive, reach out to your Tsukaeru account team.