OpenRouter popularised a simple idea: instead of integrating ten model providers, integrate one router and reach all of them through a single API. It is a genuinely good idea — so good that there is now a whole category of LLM routers and gateways to choose from. This guide compares the landscape honestly: what these tools actually do, how routing works under the hood, the trade-offs between managed and self-hosted, the total cost of ownership, and where an INR-billed router for India fits.
Key takeaways
• An LLM router gives you one API, one key, and the ability to switch or fail over between models without rewriting code.
• The real choice is along a few axes: managed vs self-hosted, OpenAI-compatibility, billing currency, observability and region.
• Most aggregators bill in USD. If you need INR/UPI billing and a GST invoice, that narrows the field fast.
• Ollima is the India-first option: one OpenAI-compatible key, rupee billing, GST invoice, free 50K tokens/day.
What an LLM router actually does
Strip away the marketing and a router does five jobs:
- Unification. One API surface in front of many providers, so your app speaks one dialect.
- Model switching. Change the model with a string, not a new SDK, key or billing account.
- Resilience. Retries and failover when a provider is down, throttled, or slow.
- Governance. Central keys, spend caps, and per-team limits.
- Observability. One place to see usage, cost and latency across every model.
If you only ever call a single model from a single provider, you may not need a router. The moment you want a second model — for cost, for fallback, or for a capability the first one lacks — a router pays for itself.
How routing works under the hood
It helps to picture the path a single request takes, because that path is exactly what you are buying when you choose a router:
- Your app sends one request in a standard shape (for most routers, the OpenAI chat-completions format) to the router's single endpoint.
- The router authenticates your key and applies governance — is this key within its spend cap and rate limit?
- It resolves the model. Your
modelstring maps to a concrete upstream model (sometimes via an alias, so "fast" or "cheap" can point at whatever currently fits). - It calls the provider with the right auth and request translation, streaming the response back if you asked for streaming.
- On trouble, it retries or fails over — a 429 or timeout can trigger a backoff and, if configured, a fall back to an alternate model rather than an error to your user.
- It normalises and returns the response in the same shape, and logs the request — tokens, cost, latency, which model served it — for your dashboard.
Two things follow from this. First, the router is a real piece of infrastructure on your hot path, so its reliability and latency matter. Second, almost everything valuable a router does — failover, governance, observability — happens in steps 2, 5 and 6, which is why "it just adds a hop" badly undersells it.
The axes that actually matter when choosing
"Which router is best" is the wrong question. "Best for what" is the right one. Evaluate along these axes:
Managed vs self-hosted
A managed router (hosted SaaS) is the fastest path — sign up, get a key, ship. A self-hosted gateway gives you control, data residency and no per-request middleman, at the cost of running and maintaining the infrastructure yourself. Pick managed unless routing infrastructure is something your team needs to own.
OpenAI-compatibility
A router that exposes an OpenAI-compatible API is a near drop-in for the huge ecosystem of tools built around the OpenAI SDK. A bespoke API locks you into that vendor's client. Favour compatibility — it keeps your exit cheap.
Billing currency and tax
This is the axis most comparisons skip. Many aggregators bill in USD, which for Indian teams means forex markup, card-decline risk, and a receipt that is not a GST tax invoice. A router that bills in INR over UPI and issues a GST invoice is a different product for that audience.
Observability and spend control
Can you see per-request cost and latency live? Can you set a hard spend cap per key so a runaway loop can't empty your balance? These features separate a toy from something you can put in production.
Region and support
Latency, data-residency expectations, payment rails, invoice format and support hours all skew by region. A globally-generic router and a region-specific one are optimising for different users.
LLM routers and gateways compared
A category-level comparison (not a benchmark of specific vendors' private numbers, which change constantly — always check each provider's current docs and pricing):
| Approach | Hosting | OpenAI-compatible | Billing | Best for |
|---|---|---|---|---|
| Global aggregator (e.g. OpenRouter-style) | Managed | Usually yes | Typically USD | Widest model catalog, global teams |
| Cloud provider gateway (hyperscaler AI gateway) | Managed | Varies | Cloud bill (USD-centric) | Teams already deep in one cloud |
| Open-source gateway (self-host) | Self-hosted | Often yes | You pay providers directly | Control, data residency, custom routing |
| Roll your own | Self-hosted | Your choice | Direct to providers | Routing is your core IP |
| Ollima | Managed | Yes | INR / UPI + GST invoice | Indian devs, INR billing, one key |
The honest summary: if you are a global team chasing the longest model list, a global aggregator is a fine default. If you want control, self-host an open-source gateway. And if you are in India and tired of USD billing, forex markup and missing GST invoices, that is precisely the niche Ollima was built for.
Routing strategies worth knowing
A router is only as useful as how you route. These are the patterns that save the most money and pain — a good router lets you express them as configuration, not code:
- Cost-tiered routing. Default every request to a cheap open-weight model, and escalate to a premium model only on the calls that genuinely need it. This is the single biggest lever on your bill, because most traffic is routine.
- Failover routing. Pair each model with a fallback. When the primary throttles or errors, the request continues on the backup instead of failing — your uptime stops depending on any one provider.
- Capability routing. Send vision requests to a vision-capable model, long documents to a long-context model, and everything else to your cheap default — automatically, by request shape.
- Latency-aware routing. For user-facing chat, prefer the fastest model that clears the quality bar; for background jobs, prefer the cheapest. Different SLAs, different routes.
- A/B and shadow testing. Try a new model on a slice of traffic and compare cost and quality before you switch everyone — a router makes this a config change, not a deploy.
The thread connecting all of them: the right model per request, chosen without changing your application code. That is the whole reason the category exists.
Router features worth checking before you commit
Two routers can both claim "access to every model" and still be very different products. Before you integrate, look past the model list at the features that determine whether it survives production:
Failover and retries
When a provider returns a rate-limit error or times out, what happens? A good router retries with backoff and can fall back to an alternate model automatically. A weak one passes the error straight to your user. Ask specifically how failover is configured and whether it is automatic. See how Ollima handles this in rate limits.
Spend caps and budgets
A single buggy loop can spend a frightening amount overnight. A router with per-key spend caps lets you set a hard ceiling so the worst case is a stopped key, not a drained balance. If a router can't cap spend, that is a real risk in production.
Observability
You cannot optimise what you cannot see. Look for live per-request cost, latency and token counts, and the ability to break usage down by key or model. This is how you discover that one feature is quietly eating 70% of your bill.
Streaming and tool calling
If your app streams responses or uses function/tool calling, confirm the router supports both cleanly across the models you care about. Compatibility gaps here surface as subtle bugs, not loud errors.
Latency and routing transparency
Every router adds a hop. A well-run one adds little; a poorly-run one adds noticeable latency. Just as important is knowing which model actually served a request when failover kicks in — opaque routing makes debugging painful.
Security and data considerations
A router sits in the path of every prompt and response, so it deserves the same scrutiny as any third party that sees your data. Check these before you route production traffic through anything:
- Who sees your prompts. Your data passes through the router to the upstream provider. Understand both parties' data-use and retention policies — especially whether traffic is used for training.
- Key handling. Prefer a router where you hold one key to the router, not one where you hand over every provider key. Rotate and scope keys; use per-key spend caps as a blast-radius limit.
- Data residency. If you have regional requirements, ask where requests are processed and logged. This is a common reason teams choose a self-hosted gateway or a region-aligned provider.
- Sensitive workloads. For genuinely private code or data, the safest option is to keep it local (an open-weight model on your own machine) and route only non-sensitive traffic to the cloud.
- Auditability. A central log of who called what, when, and at what cost is a security feature, not just an ops one — it is how you investigate a leaked key or an anomaly.
Should you self-host or build it yourself?
Self-hosting an open-source gateway is attractive on paper — no middleman, full control. Before you commit, price in what you are taking on:
- Failover logic that is correct under partial outages and rate limits.
- Billing reconciliation across multiple provider invoices, in multiple currencies.
- Observability — usage, cost and latency dashboards you would otherwise get for free.
- Uptime — your router is now a single point of failure you must keep alive.
- Tax compliance — if you are in India, you still need GST-correct invoicing somewhere.
Build it yourself only if intelligent routing is a differentiator for your product. Otherwise a managed router is almost always the cheaper total-cost-of-ownership.
Total cost of ownership: managed vs self-hosted
The sticker comparison ("managed has a margin, self-hosting is free") is misleading because self-hosting moves the cost from a bill to your team's time. A fairer view:
| Cost | Managed router | Self-hosted gateway |
|---|---|---|
| Initial setup | Minutes (sign up, key) | Days (deploy, configure, test failover) |
| Ongoing maintenance | None — vendor's job | Patching, upgrades, dependency churn |
| On-call / uptime | Vendor's SLA | Yours — it's a single point of failure |
| Observability | Built in | You build/run it |
| Billing & tax | One invoice (INR/GST with Ollima) | Reconcile many provider invoices yourself |
| Per-request fee | A margin over provider cost | None — but you pay providers directly |
For a small team, the engineering hours to build and keep a gateway healthy usually dwarf any per-request margin a managed router charges. Self-hosting wins on cost only at large scale, or when control and residency are non-negotiable requirements rather than nice-to-haves.
When you probably don't need a router at all
Honesty cuts both ways — a router is not always the right call. You can comfortably skip one if:
- You use exactly one model and have no intention of changing. The indirection buys you little until you want a second option or failover.
- You are deep inside a single cloud's ecosystem and that cloud's own gateway already covers your models, billing and governance.
- Your volume is tiny and ad-hoc — a weekend script that calls a model a few times doesn't need routing infrastructure.
The moment any of those changes — a second model, real traffic, a need for failover or spend control, or a billing/tax requirement your current provider can't meet — a router stops being optional. For most Indian teams, the billing-and-tax requirement is what tips the balance first.
Migrating from OpenRouter (or OpenAI) to Ollima
Because Ollima is OpenAI-compatible, migration is mostly mechanical — two lines change and your request code stays the same:
from openai import OpenAI
# Before — OpenRouter
client = OpenAI(base_url="https://openrouter.ai/api/v1", api_key="sk-or-...")
# After — Ollima (same SDK, two lines change)
client = OpenAI(base_url="https://api.ollima.com/v1/", api_key="sk-...ollima...")
resp = client.chat.completions.create(
model="deepseek-v4", # map your model string
messages=[{"role": "user", "content": "Hello"}],
) The full process:
- Sign in at app.ollima.com and grab a key — ₹50 credits, no card.
- Change your base URL to
https://api.ollima.com/v1/and swap in the Ollima key. - Map your model strings to Ollima's catalog — browse the models page.
- Set a spend cap per key, then watch requests in the dashboard.
Step-by-step instructions live in the migrate-from-OpenRouter and migrate-from-OpenAI guides. Streaming and tool calling carry over unchanged because both routers speak the same API shape.
Which should you choose?
| If you want… | Choose… |
|---|---|
| The longest possible model list, global team | A global aggregator |
| Full control, data residency, no middleman | A self-hosted open-source gateway |
| Routing as your own product IP | Build it yourself |
| INR/UPI billing, GST invoice, one key, India-first | Ollima |
Three myths about LLM routers
Myth: "A router just adds latency and a markup for nothing."
A router does add a hop, but a well-run one adds little — and in exchange you get failover, observability, spend caps and one billing relationship. For most teams those features are worth far more than the milliseconds. The "markup for nothing" framing ignores everything the router does between your request and the model.
Myth: "Routers are only for people using many models."
Even with one model today, a router future-proofs you: the day a better or cheaper model ships, you switch with a string instead of a migration. It also gives you failover for that single model when the provider has a bad day. Optionality has value before you exercise it.
Myth: "OpenAI-compatible means they're all interchangeable."
Compatibility makes switching easy, not identical. Billing currency, tax handling, spend controls, observability depth, region and support differ enormously between OpenAI-compatible routers. Compatibility is the floor, not the comparison.
A short decision checklist
Run any router you are considering through these questions before you commit:
- Is it OpenAI-compatible, so your exit stays cheap?
- Does it bill in the currency you actually use, with a tax-correct invoice?
- Can you set a hard spend cap per key?
- Is there live observability — cost, latency, tokens?
- Does failover happen automatically, and can you tell which model served a request?
- Does it support streaming and tool calling on the models you need?
- Is the region, latency and support aligned with where you operate?
For Indian teams, the currency and tax line is usually the deciding one — and the reason Ollima exists.
Frequently asked questions
What is an LLM router?
An LLM router (or gateway) sits between your app and many model providers behind a single API. You send one request; the router forwards it to the chosen model, handles auth, billing, retries and failover, and returns a normalised response — so switching models is a config change, not a rewrite.
Why look for an OpenRouter alternative?
Common reasons: you need INR/UPI billing and a GST invoice (most aggregators bill in USD), you want self-hosting and full control, you want tighter spend caps and observability, or you simply want a provider built for your region. The right choice depends on which of these matters most to you.
Should I build my own router instead?
You can — open-source gateways exist — but you then own retries, failover, rate-limit handling, billing reconciliation, observability and uptime. For most teams the engineering time costs more than a managed router. Build only if routing logic is your core differentiator.
How is Ollima different?
Ollima is a managed, OpenAI-compatible router built for India: one key to all major models, billing in INR over UPI, and a GST-compliant tax invoice through a Merchant of Record. The free tier is ₹50 credits and 50,000 tokens/day, no card.
Will switching routers break my code?
If both the old and new router are OpenAI-compatible, switching is mostly a base-URL and API-key change. Ollima is OpenAI-compatible, so an existing OpenAI or OpenRouter integration migrates with minimal edits — see the migration docs.
Does a router make my requests slower?
A router adds one network hop, so there is a small overhead — but a well-run router adds little, and what you get back (failover, observability, spend caps, one bill) is worth far more than the milliseconds for most apps. If a few ms of overhead is genuinely unacceptable, you likely have a specialised low-latency need and should measure it directly.
Can I keep using the OpenAI Python SDK with a router?
Yes, if the router is OpenAI-compatible. With Ollima you keep the official OpenAI SDK and only change the base URL and API key — streaming and tool/function calling continue to work the same way.
Does failover happen automatically?
With Ollima, routing handles retries and can fall back across models so a single provider hiccup does not become your user's error. See the rate-limits doc for how it behaves and how to reason about which model served a request.
Can I self-host Ollima?
Ollima is a managed service — that is the point of it for teams who do not want to run routing infrastructure. If self-hosting and full control are hard requirements for you, an open-source gateway is the right category; if you want INR billing and zero ops, managed Ollima is the fit.
One key, every model, billed in rupees
An OpenAI-compatible router built for India — INR over UPI, GST invoice, live spend dashboard. Start free with ₹50 credits and 50,000 tokens a day, no card.